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Gohar Science 7 2 Key Book

CONTENTS

Unit

No.

Chapter Page

No.

Unit 1 What is Science? 3

Unit 2 Digestion and Respiration in Human 7

Unit 3 Transport in Human and Plants 13

Unit 4 Plant Reproduction: Flowers 19

Unit 5 Living Together in an Environment 24

Unit 6 Water 30

Unit 7 Structure of an Atom 35

Unit 8 Changes and Processes Around Us 40

Unit 9 Transmission of Heat 45

Unit 10 Refraction and Dispersion of Light 50

Unit 11 Waves and Sound 55

Unit 12 Electricity 60

Unit 13 Exploring and Space 65

Modal Paper 70

Scheme of Study 134


Unit-1

What is Science?

Section Review-1

Q.1: What is science?

Ans: Science is the system of acquiring knowledge through

observation and experimentation.

Q.2: What do engineers do?

Ans: They design and make new machines for industry.

Q.3: Write the stages of the scientific method.

Ans: 1. Stating the problem

2. Gathering information on the problem

3. Forming a hypothesis

4. Experimenting

5. Recording and analyzing data

6. Stating a conclusion

Q.4: Which are main branches of science? Define

chemistry.

Ans: The main branches of science are:

Physics, Chemistry, Biology and Mathematics.

Chemistry is the study of matter.

Q.5: What things do interest mathematicians?

Ans: They solve problems, design buildings, rockets,

aeroplanes etc. by using mathematical calculations.

Section Review-2

Q.1: Write three contributions of Al-Razi in science.

Ans: 1. He classified substances as plants, animals

and minerals.

2. He found the treatment of kidney and bladder

stones.

Q.2: Who is the founder of modern Algebra?

Ans: Al-Khwarizmi is the founder of modern algebra.

Q.3: Who discovered radioactivity?

Ans: Madam Curie and her husband Pierre Curie

discovered radioactivity.


Q.4: Define the unit. What is the unit of mass?

Ans: A unit is a standard quantity. Units are used in

measurement. The unit of mass is Gram (gm) and

Kilogram (Kg).

Q.5: What was the name of the inventor of ball point

pen?

Ans: John Loud

Chapter Review

Complete each of the following sentences with the

words given below that will make the sentence

correct.

calculation conclusion doctors

hypothesis experiment measurements

mass unit

1. A hypothesis provides direction to a scientific

project.

2. Kilogram is the unit of mass.

3. A mathematician uses the method of calculation

to solve problems.

4. On the basis of analysis of the recorded data, a

scientist comes to a conclusion.

5. A unit is a standard quantity.

6. Doctors use medicines and surgical techniques to

cure diseases.

7. Scientists cannot work without measurements.

8. Experiment is the most important part of a

scientist‟s work.

Tick () the letter of the best answer.

1. A hypothesis is tested by a (n):

(a) conclusion (b) data

(c) experiment (d) inference

2. Scientists which discover new stars and other

heavenly bodies are called:

(a) doctors (b) chemists

(c) mathematicians (d) astronomers

3. A suggested solution to a problem is called:

(a) an experiment (b) a hypothesis


(c) a conclusion (d) a statement

4. The branch of science which deals with the study

of force, energy and motion of objects is called:

(a) physics (b) chemistry

(c) biology (d) mathematics

5. Who studies plants, animals, microorganisms and

their behaviours?

(a) a chemist (b) a biologist

(c) a geologist (d) a physicist

6. Degree Celsius (°C) or Degree Fahrenheit (°F) are

units of:

(a) time (b) volume

(c) length (d) temperature

7. Kitab Al-Mansuri and Al-Hawi are written by:

(a) Al-Dinawari (b) Al-Razi

(c) Al-Khwarizmi (d) Al-Haitham

8. Who is the founder of modern algebra?

(a) Newton (b) Al-Dinawari

(c) Al-Khwarizmi (d) Al-Razi

9. Oxygen gas was discovered by:

(a) Charles Darwin (b) Joseph Proust

(c) Marie Curie (d) Joseph Priestly

10. Who discovered radioactivity?

(a) Marie Curie (b) Michael Faraday

(c) Joseph Priestly (d) Charles Darwin

11. The safety pin was invented by:

(a) John Loud (b) Alessandro Volta

(c) Stephen Poplawski (d)Walter Hunt

Answer the following questions in detail.

Q.1: Describe different stages of the scientific method.

Ans:

(i) Stating the problem:

The first step is to give a statement about the

problem.

(ii) Gathering information on the problem:

In the second step scientists collect information on

the problem from the scientific literature.

(iii) Forming a hypothesis:


From the information scientists suggest solution of

problem called hypothesis.

(iv) Experimenting:

To test hypothesis scientists perform activities to

record result. These activities are called experiments.

(v) Recording and analyzing data:

In this step scientists analyze the recorded data of

experiments.

(vi) Stating a conclusion:

On the basis of analysis of recorded data, the scientists come to a conclusion. Conclusion is the solution of problem.

Q.2: Write briefly about the measurement of time,

length, mass, temperature and volume.

Ans: Time is measured in seconds (sec), minutes (min) and hours (hrs). Length is measured in meters (m), centimeters (cm), millimeters (mm) and kilometers (km).

Mass is measured in grams (gm) and kilograms (kg). Temperature is measured in Degree Celsius (°C) or

Degree Fahrenheit (°F). Volume is measured in cubic centimeter (cm³), liters

(l) and milliliter (ml) Q.3: Write contributions of the following scientists:

(a) Musa Al-Khwarizmi (b) Madame Curie

Ans: (a) Musa Al-Khwarizmi He is the founder of modern algebra. He introduced Arabic numerals. He gave the concept of zero. He introduced the decimal position system. (b) Madame Curie

She discovered radioactivity in radium. She designed the first mobile X-ray machine for injured soldiers. She discovered that radiation could kill human cells.


Unit-2

Digestion and Respiration in

Human

Section Review-1

Q.1: Define digestion.

Ans: The process of changing the food into simpler form is

called digestion.

Q.2: Which enzyme changes starch to sugar in our

mouth?

Ans: Amylase in our mouth changes starch to sugar.

Q.3: Write a few sources of protein.

Ans: Meat, fish, poultry, eggs and milk are rich sources of

protein.

Q.4: What are the functions of mineral salts in our

body?

Ans: They make the bones and teeth healthy. They make

the blood rich and maintain normal growth.

Q.5: How many kinds of teeth are present in our

mouth?

Ans: There are four main kinds of teeth in our mouth. They

are incisors, canines, premolars and molars.

Q.6: Where does digested food absorb in our blood?

Ans: In blood food is absorbed in the finger like

projections called “Villi” containing blood capillaries.

Section Review-2

Q.1: Write a few sources of carbohydrates.

Ans: Fruits, vegetables and grain products are good sources

of carbohydrates.

Q.2: Which enzyme helps in the digestion of proteins in

your body?

Ans: Pepsin enzyme helps in the digestion of proteins in

our body.

Q.3: Where is the fat part of your food digested?


Ans: The fat part of our food is digested in the small

intestine only.

Q.4: What is diarrhea?

Ans: Excessive discharge of stool is called diarrhea.

Q.5: Write a few symptoms of dehydration.

Ans: It‟s symptoms include, dry skin, thirst, less frequent

urination, and fatigue etc.

Q.6: Give few preventive measures to avoid

constipation.

Ans: Eat lots of fibers, drink plenty of fluids each day, take

regular exercise, go to the washroom when you need

etc.

Section Review-3

Q.1: What is respiration?

Ans: The process in which energy is released by the use of

food and oxygen is called respiration. Carbon dioxide

and water vapour are released as a result of

respiration.

Q.2: Which blood vessels in the lungs help your body

take in and give off gases?

Ans: Alveoli in the lungs let our body to take in and give

off gases.

Q.3: Compare briefly the breathing and the burning.

Ans: Similarity: Both processes produce carbon dioxide

and water vapours.

Difference

Breathing Burning

Oxygen is used in

this process.

Fuel is used in this

process.

Q.4: What causes air to move in and out of the lungs?

Ans: When space inside the chest increases, the lungs

expand and air rushes in. When space inside the chest

gets smaller, the lungs contract and air moves out of

the lungs.

Q.5: Which bacterium is responsible for the

tuberculosis?


Ans: A bacterial infection called „Mycobacterium

tuberculosis‟ is responsible for the tuberculosis.

Chapter Review



correct. esophagus amino acids alveoli duodenum

peristalsis larynx diaphragm

1. Proteins change into amino acids during their

digestion.

2. The reverse process of peristalsis is called

vomiting.

3. The esophagus is a large tube that runs from the

mouth to the stomach.

4. The first part of small intestine is called

duodenum.

5. The grape-like clusters of tiny thin-walled

balloons in lungs are called alveoli.

6. Larynx is the upper part of a windpipe in our

throat.

7. The dome-shaped muscle at the bottom of our

chest is called diaphragm.


1. Most digestion occurs in the:

(a) duodenum (b) liver

(c) stomach (d) large intestine

2. Water is absorbed in the:

(a) liver (b) esophagus

(c) small intestine (d) large intestine

3. Who produces enzymes for the final digestion of

proteins, fats, and carbohydrates?

(a) mouth (b) large intestine

(c) pancreas (d) gallbladder

4. Carbohydrates are best obtained from:

(a) milk (b) meat


(c) grains (d) eggs

5. Which teeth are taller and pointed for piercing,

slashing and tearing the food?

(a) incisors (b) canines

(c) premolars (d) molars

6. When you inhale, your _________ contract (s)

and move (s) down.

(a) bronchioles (b) alveoli

(c) diaphragm (d) kidneys

7. Air is moistened, filtered, and warmed in the:

(a) larynx (b) nasal cavity

(c) pharynx (d) trachea

8. Exchange of gases occurs between the______ and

capillaries.

(a) alveoli (b) bronchioles

(c) bronchi (d) trachea

9. An infection of the nose and throat caused by the

virus is:

(a) constipation (b) diarrhea

(c) common cold (d) appendicitis

10. The rib cage _________ when you exhale.

(a) moves up (b) moves out

(c) moves down (d) stays the same Answer the following questions in detail. Q.1: Explain the process of digestion of food in the

mouth and the stomach. Ans: Digestion of food in the mouth:

Our tongue mixes the pieces of food with saliva. It is

produced by salivary glands which further produce

amylase (ptyalin). Amylase starts the chemical

breakdown of starch (carbohydrates) to sugar, and

food in the mouth becomes a soft mass called bolus.

Bolus is moved to the pharynx and then to esophagus.

Digestion of food in the stomach:

In stomach the churned food is bathed with gastric

juice. Hydrochloric acid and pepsin kill the germs and

digest the protein part of food respectively. Mucus


protects the stomach from strong acids. Then food

changes into chime, and chime moves to the small

intestine.

Q.2: Describe the digestion of carbohydrates and

proteins.

Ans: Digestion of carbohydrates:

In the mouth, amylase breakdown the carbohydrates

and are converted to the glucose. The remaining

digestion is occurred by the pancreatic juice in the

first part of small intestine.

Digestion of proteins:

In the stomach, the protein part of food is digested

with the help of pepsin enzyme and protein changes

into amino acids. The remaining digestion is occurred

by trypsin enzyme, present in pancreatic juice in

small intestine. Q.3: Explain the respiratory system of human. Ans: The respiratory system of human consists of

following organs. Nasal Cavity: It helps in getting air inside the body. The nasal hair

and mucus glands are present in the nostrils. Hair and mucus trap the dust, pollen and other materials inside the nostrils. Pharynx and Larynx: The moist and clean air now moves into the pharynx, which lead to respiratory system. Next to pharynx is larynx. Vocal cords are present in larynx to produce sounds. Trachea: Air passes from the larynx into the trachea. The trachea is lined with mucus membrane and cilia to trap dust. Bronchi and Lungs:

Air from trachea enters into the bronchi. Then it

enters into lungs which consist of bronchioles. Each

bronchiole has tiny balloons called aveoli. Here

oxygen of the air enters the blood and carbon dioxide

leaves the blood in alveoli. Carbon dioxide leaves our

body when we breathe out.


Q.4: Write notes on the following: i. Breathing process ii. Common cold Ans: i. Breathing process

Breathing process consists of inhaling and exhaling

processes. When we inhale, diaphragm tightens and

moves down, and space inside the chest increases.

Then lungs expand and air rushes in.

When we exhale, diaphragm relaxes and moves up,

and space inside the chest becomes less. Then air is

forced out of the lungs, as the chest gets smaller.

ii. Common cold

It is a respiratory illness with runny nose. It spreads

by coughing, sneezing or touching. Its symptoms

include sore throat, cough, headache and sneezing etc.

Its treatment includes getting lots of rest, drinking

plenty of water etc.


Unit-3

Transport in Human and Plants

Section Review-1

Q.1: What is pericardium? Ans: A sac in which heart is enclosed, is called as

pericardium. Q.2: Name the parts of blood. Ans: Plasma, red blood cells, white blood cells, platelets. Q.3: Write three functions of blood. Ans: It helps in the distribution of food and oxygen in the

body. It helps in the distribution of heat in the body. It also helps in healing wounds and in over coming bacteria.

Q.4: What is the function of haemoglobin in red blood cells?

Ans: Haemoglobin transports oxygen and carbon dioxide. Q.5: What is sphygmomanometer? Ans: A device which doctors use to measure blood

pressure is called sphygmomanometer. Q.6: Which blood vessels help in exchange of materials

in your body? Ans: Arteries help in the exchange of materials between

blood and tissues.

Section Review-2

Q.1: What is atherosclerosis?

Ans: The thickening of the inner lining of the arteries is

called atherosclerosis.

Q.2: Which complications are related to diabetes?

Ans: Heart disease, kidney failure and blindness etc.

Q.3: What is asthma?

Ans: Asthma is a disorder of lungs which causes the attack

of wheezing, shortness, coughing etc.

Q.4: How can you avoid heart disease?

Ans: We can avoid heart disease by taking regular

exercise, avoiding smoking and taking foods high in

fiber.


Q.5: Which disorder of the circulatory system is called

the silent killer?

Ans: High blood pressure is called the silent killer.

Section Review-3

Q.1: Which are the major tissues of transportation in plants?

Ans: Xylem and Phloem are the major tissues of transportation in plants.

Q.2: What is osmosis? Ans: The movement of materials across the membrane is

called osmosis. Q.3: Define active transport. Ans: Movement of materials from a region of lower

concentration to the region of higher concentration by the use of energy is called active transport.

Q.4: What is transpiration? Ans: The evaporation of water from the surface of leaves

of plants through stomata and the resultant pull of water from the plant roots and soil, is called as transpiration.

Q.5: Where does most of the photosynthesis take place in a plant?

Ans: Most of the photosynthesis occurs in the chloroplast of plant cells because it contain chlorophyll which absorb sunlight.

Q.6: On which surface of leaf more stomata are present?

Ans: More stomata are present in the lower surface of leaf.

Chapter Review

Complete each of the following sentences with the words given below that will make the sentence correct. Diffusion health plasma heart phloem herbaceous pancreas 1. Diffusion is the movement of materials from a

region of higher concentration to the region of

lower concentration.

2. Some plants have woody stems, others have

herbaceous stems.


3. The liquid part of our blood is called plasma.

4. Any disorder in our circulatory system can affect

our heart.

5. The food is transported in a plant body through

phloem.

6. Diabetes is a disorder of pancreas.


1. Blood is carried away from the heart in:

(a) arteries (b) veins

(c) nerves (d) ureters

2. Where does the exchange of food, oxygen and

wastes occur?

(a) in arteries (b) in veins

(c) in capillaries (d) in lymph vessels

3. Blood functions to:

(a) digest food (b) dissolve bone

(c) produce carbon dioxide

(d) carry oxygen

4. Infection is fought off by:

(a) red blood cells

(b) white blood cells

(c) bones (d) nerves

5. One is not the risk factor for diabetes:

(a) obesity

(b) high blood pressure

(c) normal cholesterol level

(d) physical inactivity

6. One may be the symptom of asthma:

(a) blurred vision (b) extreme hunger

(c) frequent urination (d)chest pain

7. Movement of materials in a plant from a region of

lower concentration to the region of higher

concentration by the use of energy is called:

(a) osmosis (b) transpiration

(c) active transport (d) diffusion


8. Which tissue of a plant transports water and

minerals from roots to leaves?

(a)xylem (b) phloem

(c) bark (d) mesophyll

9. The movement of prepared food from leaves to

those parts of plant body where it is needed is

called:

(a) transpiration (b) translocation

(c) osmosis (d) active transport

10. The cells that contain haemoglobin are:

(a) platelets (b) bone cells

(c) white blood cells (d) red blood cells


Q.1: Describe the structure of human heart.

Ans: Structure of human

heart:

Our heart is an incredible

strong organ made of

muscles. It is about the

size of our fist. It is

enclosed by a sac called

pericardium. There are

four chambers in our

heart left and right atria

and left and right

ventricles.

aortavena cava

A valve separates the each atrium from ventricle

below.During a single heartbeat, the two atria contract

and push blood to the ventricles below. Left ventricle

receives oxygenated blood and right ventricle receives

deoxygenated blood.

Q.2: List and describe the four components of blood and

their functions.

Ans: Plasma, red blood cells, white blood cells and platelets

are the four components of the blood.


• Plasma: It is the liquid part of blood and consists of

about 90% water. Food particles, minerals, oxygen and

proteins etc are present in it.

• Red Blood Cells: These are disc-shaped cells with a

protein “haemoglobin”. Haemoglobin transports

oxygen and carbon dioxide.

• White Blood Cells: They are bigger but less in number

than red blood cells. They fight against bacteria, viruses

that attack our body.

• Platelets: Platelets are of irregular shape. They are

short lived with a life span of five to nine days. They

help to clot the blood in case of injury.

Q.3: Describe that structure of a plant root permits the

movement of materials.

Ans: Structure of plant root:

As the seed germinates, its newly emerged root begins

making its way down into the soil to search water and

minerals. The root hairs force their way between water

coated soil particles. The large space between cells of

the root cortex allow water and air to pass from the root

hairs to the core of the root. Roots have xylem tissues

to move water and minerals from the ground to the

leaves. Phloem tissues permit the movement of food

from leaves to roots. Q.4: Write brief notes on:

i. Transpiration ii. Translocation iii. Diabetes iv. Asthma

Ans: i. Transpiration

Once in the xylem vessels, water forms unbroken

columns from the root into the leaves. From leaves

water evaporates through tiny openings called stomata.

This process is called transpiration. The lost water is

replaced by the water behind in the xylem of leaf veins,

midrib stem and roots.

ii. Translocation


The movement of prepared food from leaves to those

parts of plant body where it is needed is called

translocation. The prepared food is carried by phloem

to all parts of a plant.

iii. Diabetes

Diabetes is a disease in which blood glucose levels are

above normal. Its symptoms may include excessive

thirst, dry skin, blurred vision etc. High blood pressure

and obesity etc. are the risk factors for diabetes. The

diabetes can be reduced by taking foods with low fat

and calories, taking regular exercise etc.

iv. Asthma It is a disease which causes the attacks of wheezing,

shortness and cough etc. The triggers which cause the

asthma include dust mites, molds, pollen, stress etc.

Cough, sneezing, chest pain and sweating are the

symptoms.

We can live normal and active if we avoid from asthma

causing triggers, use plenty of water, take proper diet

and take exercise.


Unit-4

Plant Reproduction: Flowers Section Review-1

Q.1: Differentiate between asexual and sexual

reproduction.

Ans:

Sexual reproduction Asexual reproduction

1. It involves sex

organs.

2. Two organisms

produce a new

generation.

1. It does not consist of

sex organs.

2. Only one organism

produces a new

generation.

Q.2: What are the male and female parts of a flower?

Ans: Anther and filament are the male parts while stigma,

style and ovary are the female parts of a plant.

Q.3: What is pollination?

Ans: The transfer of pollen grains from the stamen of a

flower to the stigma of a carpel is called pollination.

Q.4: Name a few pollinators.

Ans: Insects, birds and bats are a few pollinators.

Q.5: Define fertilization.

Ans: The process of fusion of sperm and an egg is called

fertilization.

Q.6: Describe few characteristics of wind pollinated

flowers.

Ans: They have long stamens and carpals. They produce

plenty of lightweight pollen grains. They are dull

coloured.

Q.7: Which fruits are eaten as vegetables?

Ans: Tomato, pumpkin, cucumber and okra are eaten as

vegetables.


Section Review-2

Q.1: Which part of a seed develops into the first root?

Ans: The radical of embryo develops into the first root of

the new plant.

Q.2: Which part of the flower usually develops into the

fruit?

Ans: The ovary develops into fruit.

Q.3: What is the fruit wall called?

Ans: The fruit wall is called the pericarp.

Q.4: Why do we eat fruits?

Ans: We eat fruits to maintain our body health and to

prevent ourselves from diseases.

Q.5: What parts does the fruit of a plant contain?

Ans: Fruits consist of two basic parts:

(1) ovary (2) seed

Q.6: Which are three layers of the pericarp

surrounding the seed in most fruits?

Ans: Outer layer which is skin, middle layer which is

fleshy and inner layer which is tough or hard.

Q.7: Why is the apple not a true fruit?

Ans: The apple is not a true fruit because its flesh

originates from the part other than ovary.

Q.8: Which is the most important part of a seed?

Ans: Embryo is the most important part of a seed.

Chapter Review



correct.

embryo plumule pollinate seed

coat gametes ovules wind

endosperm

1. The seed coat protects a seed.

2. In sexual reproduction male and female gametes

fuse to form zygote.

3. The fertilized egg develops into the embryo.

4. A bee can help pollinate a flower.


5. Most grasses depend upon wind for their

pollination.

6. Ovary contains ovules which develop into seeds.

7. Plumule of the embryo develops into the first

shoot of a new plant.

8. Endosperm nourishes the embryo when it grows.


1. The part of a plant that forms seeds is the:

(a) stem (b) root

(c) leaf (d)flower

2. What helps protect seeds?

(a)fruit (b) wind

(c) bees (d) cotyledon

3. When a bee lands on a flower, it brushes against:

(a) seeds (b) cones

(c)pollen grains (d) fruit

4. Colourful flowers are usually pollinated by:

(a) clothing (b) wind

(c) birds (d)insects

5. The _________ contains food for the embryo.

(a) stigma (b)endosperm

(c) pollen grain (d) root

6. The embryonic leaves of an embryo are:

(a) root hairs (b) radicals

(c) plumules (d)cotyledons

7. The _____ is sometimes sticky part of a flower.

(a) sepal (b) stamen

(c) ovary (d)stigma

8. In some flowers, petals function to:

(a) produce ovules

(b)attract pollinators (c) protect the flower bud

(d) produce pollen grains 9. Which structure produces eggs in a flower? (a) stamen (b) petal (c)ovary (d) style

10. The union of the sperm and the egg is called:

(a) germination (b) transpiration

(c) pollination (d)fertilization



Q.1: Write a detailed note on pollination in plants.

Ans: The transfer of pollen grains from the stamen of a

flower to the stigma of the carpel is the process of

pollination. Wind, insects and animals are the agents

for pollination in different plants.

There are two kinds of pollination.

Self-pollination:

It occurs when pollen grains are transferred from the

anther to the stigma of the same flower or to the

stigma of another flower on the same plant. Pea plants

are self-pollinated.

Cross-pollination:

It occurs when pollen grains from the anther of one

plant transfer to the stigma of a flower on another

plant. Popular, willow and papaya trees are cross-

pollinated.

Q.2: Explain fertilization in plants.

Ans: The union of a sperm with a female egg is called

fertilization. In a flower the surfaces of stigmas are

sticky and pollen grains get attach to them. A pollen

tube produces from each grain in which sperms are

present. Pollen tube enters an ovule and releases its

sperm in it.

stigmapollen grain

styleovary

ovuleegg sperms

pollen tube sperms

Q.3: Describe the structure of a seed.

Ans: The upper most hard layer of seed is called testa (seed

coat). Inside the seed coat embryo is present. The

radical of embryo changes into root. The plumule of


embryo changes into shoot. Cotyledons are the food

storing parts of embryo. testa(seed coat)

radicle(root)

plumule(stem)

cotyledon(foot reservoir)

Q.4: Write a note on fruit.

Ans: The ripened ovary is called fruit. The wall of ovary

changes into pericarp. The pericarp has three layers.

The outer layer is skin, the middle layer is fleshy and

inner layer is tough or hard.

Fruits are rich in fiber, water and vitamin and keep us

healthy. Further fruits are useful for making jams, ice

creams and cakes etc. Fruits like apple, peach, pear,

orange etc. are usually used for these purposes.


Unit-5

Living Together in an

Environment Section Review-1

Q.1: Define an ecosystem.

Ans: A group of organisms in an area that interact with

each other and with their non-living environment is

called an ecosystem.

Q.2: What is a habitat?

Ans: The natural home of an organism where it lives and

reproduces is called its habitat.

Q.3: What kind of plants are found in a pond habitat?

Ans: Plants like algae duckweed, water lily, etc. are found

in a pond habitat.

Q.4: How do desert plants adapt to a desert habitat?

Ans: Desert plants have spiny, swollen leaves to store

water in their bodies.

Q.5: What factors make a tropical rain forest best

suitable for plants?

Ans: The abundant rainfall and high temperature make this

habitat best suitable for plants.

Section Review-2

Q.1: What role does sunlight play in an ecosystem?

Ans: Sunlight is the energy source in an ecosystem. Plants

use this light energy to make their own food.

Q.2: How do diseases, famines and wars bring changes

in a habitat?

Ans: They destroy lives in a habitat in a short period.

Q.3: What is predation?

Ans: A predator is an animal that has to kill the prey

(another animal) to get its food. This relationship is

called predation.

Q.4: Define humidity.

Ans: The amount of water vapour in the air is called

humidity.


Q.5: What is a parasite?

Ans: An organism that lives in or on the body of its host to

get food and shelter, is called parasite.

Q.6: In which habitat more organisms are found?

Ans: More organisms are found in the tropical rainforest

habitat.

Section Review-3

Q.1: Define adaptation.

Ans: A characteristic of an organism that makes it fit for its

environment is called adaptation.

Q.2: Which adaptations have ducks and frogs to move

in water?

Ans: The ores like working of their feet helps them to

move in water.

Q.3: How are polar bear and arctic fox able to live in

freezing cold?

Ans: These animals have thick fur on their bodies. This

thick fur helps them to live in freezing cold.

Q.4: How is chameleon adapted to its environment?

Ans: The chameleon can change its colour. This adaptation

saves it from enemies.

Q.5: What is camouflage?

Ans: The adaptation in which an animal changes its body

colour to deceive its enemy, is called camouflage.

Q.6: What are autotrophs and heterotrophs?

Ans: The living organisms that can make their own food

are called autotrophs. The living organisms which

cannot make their own food are called heterotrophs.

Q.7: Describe a food chain that includes you.

Ans:

Grass Goat Human


Chapter Review



correct. community grassland water

competition decomposers adaptation

freezing cold producers

1. Streamlined body shape is an important

adaptation for animals to move easily through

water.

2. A coniferous forest is found in freezing cold

environment.

3. Plants use solar energy to make food so, they are

producers.

4. Competition may result in change of size of some

population in a habitat.

5. Water is essential for life.

6. Grassland habitat covers about one-fourth of the

entire land on the earth.

7. A community has many populations in it.

8. Without proper control, decomposers may also

destroy useful material in a habitat.


1. The study of interactions between living

organisms and their non-living environment is

called:

(a) ecosystem (b) ecology

(c) competition (d) parasitism

2. The non-living part of any ecosystem is called

the:

(a) habitat (b) community

(c) population (d) environment

3. Organisms that make their own food are called:

(a) autotrophs (b) heterotrophs


(c) consumers (d) decomposers

4. A great variety of plants and animals is found in

a:

(a) desert habitat (b) pond habitat

(c) tropical rainforest habitat

(d) grassland habitat

5. Most organisms are active at temperatures

between:

(a) O°C and 10°C (b) 30°C and 60°C

(c) -1°C and 20°C (d) O°C and 45°C

6. Bacteria and fungi are:

(a) decomposers (b) producers

(c) grazers (d) predators

7. Seals, penguins and turtles use _______ to move

in water.

(a) fins (b) webbed feet

(c) tube feet (d) flippers

8. One plant has floating leaves and submerged

roots:

(a) hydrilla (b) cabomba

(c) water hyacinth (d) rose

9. By changing colour an animal can blend into its

surrounding and deceive its predator or prey. This

property is called:

(a) camouflage (b) mimicry

(c) predation (d) competition

10. Vultures, jackals, crayfish and snails are:

(a) producers (b)scavengers

(c) decomposers (d) predators


Q.1: Describe factors that can bring daily and yearly

changes in the habitat.

Ans: Following are the factors that can bring daily and

yearly changes in the habitat:

Light intensity, temperature, rainfall, climatic

conditions, nutrients:

Any change in light intensity (sunlight) can destroy


the vegetation. This causes the decrease of animals

number in the habitat. Plants cannot grow by the rise

or fall in temperature. Most animals can also not

survive in unsuitable temperature.

When there is no or less rainfall, there are no plants

and animals in the habitat. When there is much

rainfall, it will be cause of destruction of plants and

animals in the habitat. When there are no nutrients in

the habitat, there will be no plants and animals.

Natural climate such as excessive cold and heat,

excessive rains and drought etc. can destroy the

habitat badly.

Q.2: Describe adaptations of some aquatic animals to

live in their habitat.

Ans: Different aquatic animals adapt differently to live in

water. Streamlined body shape of shark and dolphins

help them to move easily in water. Webbed feet of

ducks and frogs help them to move in water.

Seals, penguins and turtles move in water by using

the flippers. Prawn and fish have gills to breathe in

water.

Q.3: Explain a food chain and a food web with

examples.

Ans: Food chain:

The food relationship among organisms is called a

food chain.

Example: A grasshopper eats grass, a snake may eat

this grasshopper. The snake may become the food of

a hawk. Grass → Grasshopper → Snake → Hawk

Producer Primary

consumer

Secondary

consumer

Tertiary

consumer

Food web: The combination of several food chains is

called as food web.

Example: A grasshopper and a rabbit feed on the

grass. The grasshopper next is eaten by rat and

sparrow. Rat is eaten by fox and hawk. Sparrow is

also eaten by an owl and hawk.


hawk owl

sparrow

hawk fox

rat

grasshopper

grass

Q.4: Write brief notes on:

i. Grassland habitat

ii. Effects of humidity on life

Ans: i. Grassland habitat

It is a grassy and windy area. It has fertile soil. It has

very few trees. Grazing animals like sheep, goats,

cows etc. are found there. Owls, eagles and hawks are

the birds found there.


Very low humidity is not good for plants because

moisture in the plants evaporates. In deserted areas,

wavy covering of plants helps store water in plants.

This helps plants to grow in the deserted areas.

Animals in deserted areas move to search food at

night. This helps them to conserve water in their

bodies.


Unit-6

Water

Section Review-1

Q.1: Identify the main uses of water in our body.

Ans: It helps in the blood circulation in the body. It also

helps in the transport and absorption of important

nutrients in the body.

Q.2: Why is the earth called the water planet?

Ans: Because the earth is about 97% water. It is on the

surface and beneath the surface of the earth. So, earth

is called the water planet.

Q.3: What do you mean by soft and hard water?

Ans: The water which gives rich lather with soap is called

soft water. The water which does not give good lather

with soap, but forms curds is called hard water.

Q.4: What do you mean by an artesian well?

Ans: A hole in the ground from which water is forced to

the surface by natural pressure is called an artesian

well.

Q.5: Define geysers.

Ans: The natural fountains that throw up jets of water and

steam at regular intervals through a vent in the earth‟s

surface are called geysers.

Q.6: What is a glacier?

Ans: The ice sheets made up of snow are called glaciers.

Q.7: What is an iceberg?

Ans: When large pieces of glaciers break off and float

away, then these pieces are called icebergs.

Section Review-2

Q.1: Define water pollution.

Ans: The addition of any substance that has a negative

effect on water is called water pollution.

Q.2: In a sewage water treatment plant, what is the

purpose of adding chlorine to the waste water?


Ans: The chlorine is added to kill the germs remained in

water.

Q.3: What do you mean by sedimentation in drinking

water treatment?

Ans: The process in which heavy clumps present in water,

sink down in the settling tanks is called

sedimentation.

Q.4: Define distillation of water.

Ans: The process in which water is heated to make steam

and then steam is cooled down into pure water, is

called distillation.

Q.5: Where do we use most of the water in our homes?

Ans: In homes, we use water for cleaning, washing,

flushing the toilets, cooking and drinking.

Q.6: Give a few tips to conserve water at home.

Ans: Don‟t brush your teeth with running tap water. Turn

off the shower while soaping. Wash dishes and

vegetables in a basin of water, not under running

water.

Q.7: How are agricultural chemicals polluting our

water resources?

Ans: When rain washes the fertilizers and pesticides into

the rivers and lakes, they pollute the water.

Chapter Review



correct. health salinity river permeable

pollutants acid rain bacteria fresh water

1. A river is a large natural stream.

2. Water moves easily through porous rocks which

are called permeable.

3. Dissolved salts give ocean water a property called

salinity.

4. Society is rapidly becoming more health

conscious.


5. Rivers, lakes and ponds are the sources of fresh

water.

6. Oxygen of air, and sunlight can kill many bacteria

in water.

7. Toxic gases in the air react with rain water to

make it acid rain.

8. Harmful and unwanted substances in water are

called pollutants.


1. About _______ of our body is water.

(a) 50% (b) 70%

(c) 80% (d) 90%

2. Shortage of water in the body may cause a

disease:

(a) asthma


(c) arthritis (d)all of them

3. The water that soaks into the ground is called:

(a) earth water (b) ground water

(c) water table (d) aquifer

4. A hole in the ground from which water is forced

to the surface by natural pressure is called the:

(a) well (b) artesian well

(c) tube well (d) pump

5. Running water collects in large, deep depressions

in the earth‟s crust and forms:

(a) a river (b) a stream

(c) a lake (d) a sea

6. Places where ground water bubbles or flows out

of cracks in the rocks automatically are called:

(a) geysers (b) springs

(c) icebergs (d) lakes

7. The major sources of water pollution are:

(a) human wastes (b) industrial wastes

(c) agricultural chemicals (d) all of them

8. Oil pollution is mostly caused by:

(a) major oil spills


(b) decomposed plastic materials

(c) intentional dumping of excess oil

(d) decomposed dead animals and plants

9. In a drinking water treatment plant, alum is added

to water during:

(a) aeration (b) sedimentation

(c) coagulation (d) filtration

10. We use water during showering:

(a) 10% (b) 20%

(c) 45% (d) 14%


Q.1: Explain how water is the most essential element of

life.

Ans: Water provides life to plants, animals and human. It

helps living things to grow, reproduce and carry other

functions. Without water you cannot last a week.

Clean water performs the following functions in our

body:

• removes toxins from the body

• protects body from diseases

• helps in the breakdown of food

• helps in controlling the body temperature

• helps to move blood in the body

Q.2: What makes our water impure?

Ans: The major causes of impurity of water include human

wastes, agricultural chemicals and industrial wastes.

People put garbage and sewage of the houses into the

open drains. This sewage, full of grease, toilet wastes

and detergents, make water harmful for drinking. It is

also harmful for water animals to survive. The

poisonous fertilizers of crops are washed by rain.

These poisons flow into the river water which is

dangerous for water life. Industrial wastes, mixed

with poisonous substances, are put into clean water of

rivers and canals. This cause the death of water

animals. This also pollutes the drinking water. Smoke

of power plants causes the acid rain. Acid rain kills

the aquatic life.


Q.3: How can we preserve water?

Ans: We can preserve water in the following ways.

1. Turn off shower while soaping.

2. While brushing the teeth, take water in a tumbler

instead of with running tap water.

3. Wash dishes and vegetables in a basin of water,

not under running water.

4. Water the lawn in the morning instead of

afternoon.

5. Check the leaks in water pipes and get them

repaired.

Q.4: Write steps of drinking water treatment.

Ans: Dinking water can be treated in the following steps.

1. First filter the river or lake water to remove fish,

trash, leaves etc.

2. Then add aluminum sulphate in the filtered water

to coagulate the mud, bacteria and other particles

and heavy clumps are formed.

3. Heavy clumps are settled into tanks, and lumps

sink to bottom.

4. Then water is passed through the filters to remove

the remaining impurities. Here chlorine is added

in water and allow to stand for a day or two.

5. Air is passed through the water to reduce to

unpleasant smell. Oxygen and sunlight kill

bacteria in water.


Unit-7

Structure of an Atom

Section Review-1

Q.1: What were the ideas of John Dalton about an

atom?

Ans: All matter is composed of atoms. Atoms cannot be

made or destroyed.

Q.2: What are two differences between the atomic

theory described by Thomson and that described

by Rutherford?

Ans:

Thomson Theory Rutherford Theory

1. Electrones are

embedded in

the atom.

2. Atom is a

positively

charged sphere.

1. Electrones

revolve around

the nucleus.

2. Atom is mostly

an empty space.

Q.3: In what part of an atom is most of its mass

located?

Ans: Most mass of an atom lies in its nucleus.

Q.4: Why atoms are neutral?

Ans: As the total positive charge of protons balances the

total negative charge of electrons, therefore, atoms

are neutral.

Q.5: List the names, charges, and locations of three

kinds of particles that make up an atom.

Ans: Electron: negative charge, moves around the

nucleus.

Proton: positive charge, present in the nucleus.

Neutron: neutral, present in the nucleus.

Q.6: Define valency.

Ans: The capacity of an element by which its most atoms

combine with the atoms of other element, is called

valency.


Section Review-2

Q.1: How are the isotopes of an element alike and how

are they different?

Ans: Similarity:Isotopes of an element have same number

of protons.

Difference:They have different number of neutrons.

Q.2: Use the periodic table to find the names, atomic

numbers, and average atomic masses of the

following elements: Na, Ca, Kr, W

Ans:

Element Name Atomic

number

Average

atomic mass

Na

Ca

Kr

W

Sodium

Calcium

Krypton

Tungsten

11

20

36

74

22.990

40.078

83.80

183.85

Q.3: Write three uses of isotopes in medicines.

Ans: 1. Iron – 59 is used to study iron metabolism

in spleen.

2. Bismuth – 213 is used in cancer treatment.

3. Selenium – 75 is used to study digestive

disorders.

Q.4: What does the chemical formula of a molecule

show?

Ans: Chemical formula of a molecule shows:

1. Kinds of elements in the molecule.

2. Number of atoms of each element.

Q.5: Define a molecule and an ion.

Ans: A particle made up of two or more atoms is called a

molecule. An atom with positive or negative charge is

called an ion.

Chapter Review



correct.

atomic number noble gases


electronic configuration neutron valency anion

1. Helium (He), neon (Ne), argon (Ar), krypton (Kr),

etc. are noble gases.

2. The number of electrons in the outermost shell of

an atom is also called its valency.

3. Negatively charged ion is called anion.

4. A neutron is the particle with no charge.

5. The number of protons in an atom is called atomic

number.

6. Electronic configuration is the distribution of

electrons in different shells.


1. An atom has no overall charge if it contains equal

number of:

(a) electrons and neutrons

(b) electrons and protons

(c) protons and neutrons

(d) positrons and neutrons

2. Isotopes are found because atoms of the same

element can have different number of:

(a) protons (b) electrons

(c) neutrons (d) none of the above

3. Which of the following describes what happens

when an atom becomes an ion with a 2–

charge?

(a) The atom gains 2 protons.

(b) The atom loses 2 protons.

(c) The atom loses 2 electrons.

(d) The atom gains 2 electrons.

4. In the chemical formula CO2, the subscript 2

shows which of the following?

(a) There are two oxygen ions.

(b) There are two oxygen atoms.

(c) There are two carbon atoms.

(d) There are two CO2 molecules.

5. Which term is used to represent a molecule?

(a) equation (b) chemical symbol

(c) chemical formula (d) molecular number


6. The correct chemical formula for calcium chloride

is:

(a) CaCl (b) Ca2Cl

(c) CaCl2 (d) Ca2Cl2

7. The atomic number of flourine (F) is 9. Its mass

number is 19. How many neutrons are present in

its atom?

(a) 7 (b) 8

(c) 9 (d) 10

8. The Law of Constant Composition was presented

by:

(a) Joseph Proust (b) John Dalton

(c) Rutherford (d) Niels Bohr

9. Whose statement is this?

“When electrons jump from one shell to the other,

energy is absorbed or evolved.”

(a) James Chadwick (b) Rutherford

(c) Niels Bohr (d) John Dalton

10. The number of electrons in N-shell can be:

(a) 2 (b) 8

(c) 18 (d) 32


Q.1: Describe the structure of an atom.

Ans: Structure of an atom:

Atom is made up of smaller particles and a nucleus.

They are given below.

Nucleus: Nucleus is the central part of atom having

protons and neutrons in it.

Electron: Electron is a smaller mass particle with

negative charge. It moves around the nucleus.

Proton: Proton is a positively charged particle,

present in the nucleus. Number of protons and

number of electrons are equal.

Q.2: What is an ion? How ions are formed?

Ans: Ion: An atom with positive or negative charge is

called an ion. For example sodium ion (Na+) and

chloride ion (Cl¯).


Formation of Ions: When an atom release its one or

more electrons from the outermost shell, the number

of protons increases. The positive charge appears on

atom. Therefore it is a positive ion (cation).

When an atom absorbs one or more electrons

in its outermost shell, the number of electrons

increases. The negative charge appears on atom.

Therefore, it is a negative ion (anion)

Q.3: Define the term isotope. Write about the

applications of isotopes in the fields of medicine

and agriculture.

Ans: Isotope: The atoms of the same element having same

atomic number but different mass numbers are called

isotopes. For example, Hydrogen (H) has three

isotopes, Protium 1

1( H) , Deuterium 2

1( H) and

Tritium 3

1( H) .

Isotopes are used to:

• label red blood cells

• study iron metabolism

• study genetic diseases

• investigate the nitrogen cycle in crop plants

• to detect food adulteration

Q.4: State The Law of Constant Composition and give

examples.

Ans: Law of Constant Composition: The composition of

a compound is always the same, no matter how the

compound was made or obtained.

Example 1: There are two hydrogen atoms and one

oxygen atom in water (H2O). They will be same in

the water of any place of the world.

Example 2: Carbon dioxide can be obtained in a

number of ways, but it will always consist of one

carbon atom and 2 oxygen atoms.


Unit-8

Changes and Processes Around Us Section Review-1

Q.1: What is a change?

Ans: When whole thing or a part of a thing becomes

different, we say that it has changed.

Q.2: What is meant by a physical change?

Ans: When a material is changed in size or form without

becoming another material, the change is called a

physical change.

Q.3: Define a chemical change.

Ans: When a material is changed into one or more different

materials, the change is called a chemical change.

Q.4: Give two examples of chemical change.

Ans: (1) Rusting of iron materials (2) Souring of milk

Q.5: Give an example to show that people change the

environment.

Ans: Cutting of trees to clear the land is the example in

which people change the environment.

Q.6: Define hydrocarbons.

Ans: An organic compound consisting of only carbon and

hydrogen is called a hydrocarbon.

Q.7: What is LPG?

Ans: It is the abbreviation of “Liquefied Petroleum Gas”. It

is used as a fuel in heating appliances and in vehicles.

Section Review-2

Q.1: Define hydrogenation.

Ans: The chemical process in which vegetable oil changes

into fat (Banaspati ghee) is called hydrogenation.

Q.2: What is a polymer?

Ans: A large, complex molecule made from smaller

molecules joined together, is called a polymer.

Q.3: Define plastics.

Ans: Plastics are synthetic polymers that can be molded

into various shapes.

Q.4: Write some uses of PVC.


Ans: It is used for making plastic pipes, outdoor furniture

and liquid detergent containers.

Q.5: Define a non-reversible change.

Ans: A change in which the product formed cannot be sent

back to its original form is called a non-reversible

change.

Chapter Review



correct. change corrode hydrocarbons

polymer fertility humus oil

refinery chemical change

1. Burning of paper is a chemical change.

2. Hydrocarbons react with oxygen of air and

change chemically.

3. Petroleum is processed in an oil refinery to obtain

useful products.

4. Synthetic rubber is also a polymer.

5. Farmers use fertilizers to increase the fertility of

land.

6. Our growing is also a process of change.

7. Metal statues corrode very slowly.

8. Chemical fertilizers do not add humus to the soil.


1. Lighting a match is an example of a:

(a) physical change (b)chemical change

(c) change in pressure (d) change of colour

2. A copper wire will bend. This is an example of:

(a) a chemical change (b) conservation

(c) a physical change (d) an element

3. An example of a chemical change is:

(a) boiling of water

(b) evaporation of water

(c) burning of paper

(d) melting of ice


4. The red colour of a rose turns brown. It is a:

(a) physical change (b) chemical change

(c) reversible change (d) sudden change

5. A factor that can change the environment quickly

is:

(a) a rain (b) humidity

(c)an earthquake (d) sunlight

6. A physical change takes place where matter:

(a) rusts (b) burns

(c) decays (d)condenses

7. Which one is not a polymer?

(a) plastics (b) synthetic rubber

(c) ice (d) nylone rope

8. The vegetable oil is changed into banaspati ghee

(fat) by the addition of:

(a) nitrogen (b) carbon

(c) oxygen (d) hydrogen

9. Nonstick coating of cooking pans is made from:

(a) teflon

(b) polyvinyle chloride (PVC)

(c) polypropylene (PP)

(d) polystyrene (PS)

10. Which one is a non-reversible change?

(a) rotting egg

(b) mixing of salt in water

(c) switching on a tube light

(d) wetting a dry cloth


Q.1: Explain with examples that a chemical change

brings change in the properties of a substance.

Ans: A chemical change, changes the properties of

substances. For example, shiny metal aluminum

reacts with colourless oxygen gas in air. A white

coated aluminum oxide compound is formed.

Similarly, carbon, which can burn, reacts with

oxygen, which helps in burning. They produce carbon

dioxide, which neither burns nor it helps in burning.


This shows that properties of a substance change by

chemical change.

Q.2: Discuss advantages and harmful effects of

chemical fertilizers.

Ans: Advantages:

Chemical fertilizers are easy to store and apply in

fields. They can control the amount of minerals to be

added. By using them, farmers get two crops a year.

They can be used in place of manure.

Harmful effects:

Chemical fertilizers cause the spoilage of soil. They

can pollute the water of canals and rivers. They use

much amounts of fuels. This causes the loss of our

fuel reserves.


i. Plastics

ii. Change of vegetables oil into fat

Ans: i. Plastics Plastics are synthetic polymers that can be changed

into various shapes. Alexander Parkes of England

made the earliest form of plastics in 1855. Many

things around us are made of plastics. For example,

telephone set, jars, bottles etc. Plastics are strong

enough than other natural materials. They can last for

long periods of time. Most plastics can be recycled to

use again.

ii. Change of vegetables oil into fat Vegetable oil changes into fat by the process called

hydrogenation. In this process, vegetable oil is treated

with hydrogen, in the presence of nickel. In this way

vegetable oil is changed into solid fat at room

temperature. A large amount of heat is used in this

way.

Q.4: Explain reversible and non-reversible changes

with examples.

Ans: Reversible changes can be shown by:

• melting of ice into liquid water

• switching on a tube light


• mixing of salt in water.

• Non-reversible changes can be shown by:

• breaking of glass

• burning of paper and wood

• rotting egg or fruit.


Unit-9

Transmission of Heat

Section Review-1

Q.1: Between which two objects does heat always move?

Ans: Heat always moves from warmer objects to cooler ones.

Q.2: What is conduction of heat? Ans: The transfer of heat through a material thing from hot

to the cold regions is called conduction. Q.3: Why are cooking pots made of metals?

Ans: Cooking pots are made of metals because metals are good conductors of heat.

Q.4: How does convection of heat occurs?

Ans: When heat transfers from hot part of the fluid to the cooler part by the movement of fluid itself, then convection occurs.

Q.5: What is a fluid?

Ans: Any material that flows is called a fluid. Q.6: Name four poor conductors of heat.

Ans: Wood, plastic, glass and air. Q.7: What is a convection current?

Ans: When heat is given to a fluid, then the fluid expands. The fluids from the surrounding take the place of hot fluid particles. The movement of hot and cold fluid creates a current, which is called convection current.

Section Review-2

Q.1: How does heat of the sun reach the earth?

Ans: Heat from the sun reaches the earth through radiation.

Q.2: Which surfaces absorb maximum heat?

Ans: The surfaces of greater area absorb maximum heat.

Q.3: How does a blacksmith experience all the three

ways of heat transfer? Ans: 1. When heat is transferred from forge to metal,


horse shoe in blacksmith‟s forge glows red. (conduction)

2. Heat of forge warms the air in black smith‟s shop. (convection)

3. The blacksmith feels the glow of heat from the forge. (radiation).

Q.4: Why do we use woollen clothes and blankets during winter days?

Ans: Because clothes and blankets are insulators and slow the transfer of heat of our body.

Q.5: How does convection help in household ventilation?

Ans: Convection currents carry away heat, making the room cool.

Q.6: How are ocean currents produced? Ans: Ocean currents are produced due to convection of

heat.

Section Review-3

Q.1: When you sit beside a fire, how does heat reach you?

Ans: when you sit beside a fire, the heat of fire reaches you through radiation.

Q.2: How can the food be kept hot for a longer period? Ans: To keep the food hot for a longer period, it is kept in

pots with shiny, silver and smooth surfaces. Q.3: How does surface area affect the radiation of heat?

Give an example. Ans: A spherical ice piece will melt later than a thin sheet

of ice of equal weight. Q.4: What is the advantage of gliding flight for a bird? Ans: During gliding flight a bird does not move its wings

instead glides on air currents. A lot of energy of a bird

is saved in this way.

Q.5: Why are the cooling fins at the back of your

refrigerator painted black?

Ans: The cooling fins at the back of the refrigerator need to

radiate its heat quickly to the surroundings.


Chapter Review

Complete each of the following sentences with the words given below that will make the sentence correct. free electrons fluid convection radiation conduction insulators heat energy 1. Woollen clothes and blankets are insulators that

slow the transfer of heat out of our body. 2. Thermos bottle use air or a vacuum to slow the

transfer of heat by conduction. 3. Radiation of heat requires no material medium. 4. Radiation is the fastest way to transfer heat

energy. 5. Metals have free electrons that make better heat

conduction. 6. Convection takes place more readily in gases than

in liquids. 7. Any material that flows is called a fluid.


1. Heat energy travels through a metal spoon in hot tea mostly by:

(a) radiation (b)conduction (c) convection (d) insulation 2. When a pot of water is put on a hot stove, the

water at the top gets warm mostly by: (a) radiation (b) conduction (c) convection (d) insulation 3. Energy travels from the sun to the earth by: (a) radiation (b) conduction (c) convection (d) insulation 4. What happens if two objects at different

temperatures are touching? (a)Heat energy transfers from the warmer

object. (b) Heat energy transfers from the cooler object. (c) Heat energy transfers to the warmer object. (d) No heat energy transfer takes place.


5. What is the name given to any material that transfers heat energy easily?

(a) thermal (b) metal (c) insulator (d) conductor 6. Which one is an insulator of heat? (a) air (b) mercury (c) silver (d) iron 7. Land and sea breezes blow due to: (a) conduction of heat

(b) convection of heat (c) radiation of heat

(d) emission of heat 8. Which colour is a good reflector of heat? (a) red (b) black (c) blue (d)white 9. How is the transfer of heat slowed down in a

thermos bottle? (a)by the use of a vacuum

(b) by the use of paper (c) by the use of a metal sheet

(d) by the use of wood 10. What type of energy transfer produces weather? (a) radiation (b) convection (c) conduction (d) atmospheric


Q.1: What is convection? How does it occur?

Ans: The process in which heat move from hot to cooler

part of a fluid by movement of fluid is called

convention.

When a fluid is heated, its particles move apart freely.

It means the fluid expands and becomes less dense.

The cooler fluid particles take the place of the heated

particles. In this way a stream of fluid is set up and is

called convection current.

Q.2: Write everyday applications of conduction of heat.

Ans: Conduction is very useful in our lives. Cooking

utensils, electric kettles, irons etc. are made of metals

so that heat can move easily in them. Thermos bottles


use air or a vacuum to slow the transfer of heat by

conduction.

In a factory, water and steam pipes of a boiler

are made of metal to conduct heat quickly. Double-

pan windows are used in buildings to slow the

transfer of heat. The natural insulation in birds and

mammals help to reduce the heat loss.

Q.3: Write a note on a thermos bottle.

Ans: A thermos bottle or vacuum

flask reduces the transfer of

heat. It consists of two thin

glass bottles. Air between

the glass walls is removed to

create vacuum. Vacuum

prevents transfer of heat by

conduction and convention.

The skinny and smooth glass

walls prevent transfer of

heat by radiation. The

double walled bottle is

enclosed in a plastic

container.

air space

glass

vacuum

plastic container

THERMOS


(i) Land and sea breezes

(ii) Gliding flight of birds

Ans: (i) Land and sea breezes

The land heats up fast during the day as compared to

the sea. The hot air over the land arises. The cool

breeze from the sea then blows in to take the place of

this warm arising air. In this way convection currents

in air cause breezes to blow.

(ii) Gliding flight of birds

The warm air from ground rises up. This occurs

continuously. The birds glide on air currents instead

of moving its wings. The bird‟s wings rest on piles of

rising up air. This is due to the convection of heat.

This helps the birds to save its energy during soaring

or gliding.


Unit-10

Refraction and Dispersion of

Light

Section Review-1

Q.1: What is refraction of light?

Ans: When a light ray passes from one transparent medium

to another at an angle, then light changes its direction.

It is called refraction of light.

Q.2: When light moves from air into glass at an angle,

is the light refracted toward or away from the

normal?

Ans: When angle of incidence (i) is greater than the angle

of refraction i.e., i > r, then light refracted towards the

normal.

Q.3: What is refractive index?

Ans: The ratio of speed of light in a vacuum to its speed in

another medium is called refractive index.

Q.4: Define the dispersion of light.

Ans: The splitting of white light into its component colours

is called dispersion of light.

Q.5: List the seven colours of white light dispersed by a

prism.

Ans: Violet, indigo, blue, green, yellow, orange and red

(VIBGYOR).

Q.6: How is the refractive index of a substance related

to the speed of light in that substance?

Ans: speed of light in vacuum

Refractiveindex of a substance =speed of light in the substance

Section Review-2

Q.1: What is meant by total internal reflection? Ans: When light passes from a transparent denser medium

(glass or water) to a rare medium (air) and angle of


incidence (i) is greater than the critical angle (C), the light rays reflect in the same denser medium. It is called total internal reflection.

Q.2: Briefly describe why you sometimes see a rainbow during a rain shower or shortly afterward.

Ans: When white light from the sun shines through tiny rain drops, then a rainbow appears. It is due to refraction and reflection of sunlight by raindrops.

Q.3: Why do we see the petals of a rose as red and the leaves as green? Ans: We see petals as red because petals reflect red colour

of light and absorb all other colours and leaves as green because leaves reflect green colour.

Q.4: What are the primary pigment colours? Ans: Cyan, yellow and magenta are the primary pigment

colours. Q.5: Explain the scene of seeing water on the road

ahead, while travelling on a hot, sunny day? Ans: It is due to the process called mirage. On hot, sunny

days, when light passes from cold air (upper layer) to the warm air (near earth layer) then light refracts. When total internal reflection occurs, then observer assumes that rays are reflecting from water. As a result observer sees a mirage.

Q.6: What advantages do optical fibers have over metal wires for communication?

Ans: Optical fibers can carry thousands of phone

conversations at the same time.

Chapter Review

Complete each of the following sentences with the words given below that will make the sentence correct. prism refraction critical angle mirage optical fiber refractive index incident ray 1. A mirage is an optical illusion. 2. An optical fiber can carry thousands of phone

conversations at the same time.


3. The bending of light, when it enters from one

medium to another is called refraction.

4. The light ray that enters the new medium, is

called an incident ray.

5. The angle of incidence at which maximum

refraction occurs is called the critical angle.

6. A prism is a transparent wedge-shaped block of

glass.

7. Refractive index is the ratio of the speed of light

in vacuum to its speed in another medium.

Tick () the letter of the best answer. 1. When a light ray passes from one medium to

another at an angle: (a) reflection occurs

(b) refraction occurs (c) refraction does not occur

(d) reflection does not occur 2. Refractive index of glass is: (a) 1.47 (b) 2.42 (c) 1.5 (d) 1.33 3. The splitting of white light into its component

colours is called: (a) dispersion of light

(b) reflection of light (c) interference of light

(d) irregular reflection 4. What causes a rainbow? (a) reflected light (b) absorbed light (c) artificial light (d) refracted light 5. The separate colours of white light are called the: (a) spectrum of light (b) group of colours (c) band of light (d) dispersion of light 6. We see a mirage due to the: (a) reflection of light

(b) total internal reflection (c) dispersion of light (d) spectrum of light 7. Which of the following is not a primary colour of

light?

(a) red (b) green

(c) blue (d)yellow


8. Use the phenomenon of total internal reflection:

(a) camera (b)optical fiber

(c) microscope

(d) refracting telescope

9. When all the colours of light are reflected into our

eyes, the object appears:

(a) black (b) red

(c) green (d)white

10. By mixing a magenta and cyan pigments we can

produce the colour:

(a) blue (b) green

(c) white (d) red


Q.1: Verify the “Laws of Refraction” through an

activity.

Ans: Activity

Fix a white sheet of paper on the drawing board, by

drawing pins. Place a glass slab in the middle of the

paper and draw its boundary PQRS. Fix two pins A

and B on the paper in a straight line that make an

angle with the slab. Look at the images of pins A and

B from other side. Fix two pins C and D in the line of

images of A and B. Remove the slab. Join A and B to

the PQ at point M and join C and D to SR at point L.

Now join „M‟ and „L‟. Draw normal FG at point M.

• AB is the incident ray. • ML is the refracted ray

A

B

C

D

G

M

F

L

P Q

RS

Q.2: What is the total internal reflection? Explain it

with an example.


Ans: When light from a transparent denser medium (glass

or water) passes to a rare medium (air), it refracts or

bends away from the normal. When the angle of

incidence (i) is greater than the critical angle (C), the

light rays reflect in the same denser medium. This

phenomenon is called total internal reflection.

glass

air =90o

C C

C is the critical angle

light source

refractiontotal internal

reflection

Q.3: What is dispersion of light? Why does white light

get dispersed?

Ans: Dispersion of light:

The splitting of white light into its component colours

is called dispersion of light.

When a beam of light enters a prism, each of

its component colours slows down. All the colours

refract by different angles. Therefore, it causes the

white light to split into its component colours.


Unit-11

Waves and Sound

Section Review-1

Q.1: Define a wave. Ans: A disturbance that transfers energy from place to

place, is called a wave. Q.2: Sketch a transverse wave and label a crest, a

trough, a wavelength, and amplitude.

Ans:

trough

amplitude

wavelengthcrest

Q.3: List the four basic properties of waves. Ans: (1) amplitude (2) wavelength (3) frequency (4) speed Q.4: How are the speed, wavelength, and frequency of a

wave related? Ans: Speed = wavelength × frequency V = × f Q.5: A wave travels at a velocity of 40m/sec and has a

frequency of 3.5Hz. What is its wavelength? Ans: As we know that; V = × f

So; = v

f

=40

3.5

11.42m

Section Review-2

Q.1: What type of waves are sound waves? Ans: The sound waves are longitudinal type of waves. For example, a sound travelling through air is a type of

longitudinal waves.


Q.2: What makes some sounds louder than others? Ans: The amplitude of sound waves makes some sounds

louder than others. Q.3: What is the relationship between frequency and

pitch? Ans: Higher the frequency, higher will be the pitch. i.e,

frequency × pitch. Q.4: Explain briefly, how can a musical sound shatter a

glass. Ans: When the frequency of sound of musical instruments

match the natural frequency of a crystal glass, then glass may shatter. This is due to increase in amplitude of glass particles.

Q.5: What is the unit of the loudness of a sound? Ans: It‟s unit is decibels (dB). Q.6: Define ultrasound and infrasound. Ans: When frequency of sound waves is above the normal

human range (20,000 Hz) of hearing, then these sound waves are called ultrasound. When the frequency of sound waves is below 20Hz, then these sound waves are called as infrasound.

Chapter Review

Complete each of the following sentences with the words given below that will make the sentence correct. compression vocal cords vibration medium speed musical instrument siren ear drum 1. A head injury can cause damage to ear drum. 2. A siren warns us about the danger. 3. The sound depends on the size and shape of the

musical instrument. 4. The distance a wave covers or travels in one

second is called its speed. 5. When we speak or sing, the vocal cords in our

throat vibrate. 6. A compression and a rarefaction combine to form

a longitudinal wave.


7. A material thing through which a wave travels is called a medium.

8. A vibration is a repeated to-and-fro or up-and-down motion.

Tick() the letter of the best answer. 1. A wave carries: (a) energy (b) matter (c) water (d) air 2. The distance between one crest and the next crest

is the wave‟s: (a) amplitude (b) wavelength (c) frequency (d) speed 3. In a given medium, if the frequency of a wave

increases, its: (a) wavelength increases

(b) speed increases (c) amplitude decreases

(d) wavelength decreases 4. Hertz is the unit of: (a) amplitude (b) wavelength (c) speed (d) frequency 5. A sound wave is a: (a) transverse wave (b) longitudinal wave (c) reverse wave (d) standing wave 6. Sound waves of frequency less than 20Hz are

called: (a) ultrasound (b) infrasound (c) ultraviolet waves (d) infrared waves 7. Hitting an object harder will make the volume: (a) softer (b) the same (c) lower (d) louder 8. Objects that vibrate slowly have a pitch that is: (a) high (b) loud (c) soft (d) low 9. The lowest parts of a transverse waves are called: (a) crests (b) compressions (c) rarefactions (d) troughs 10. Sound waves travel most quickly through: (a) solids (b) gases (c) air (d) liquids



Q.1: Describe the basic properties of waves.

Ans: These are four basic properties of waves.

Amplitude, wavelength, frequency and speed:

The term amplitude is used to know the size of a

wave. The amplitude of a transverse wave is the

maximum distance from the rest position to a crest or

to a trough.

rest position

amplitude

wavelength

The distance between two adjacent crests or troughs

is called the wavelength. It can be measured in millimeters (mm), cm and „m‟. The number of waves that pass a given point in one second is called the frequency of a wave. Its formula is:

Frequency is measured in hertz (Hz). The distance a

wave travels in one second is called its speed. It‟s formula is;

Speed = distance covered

time (in seconds) Speed is measured in meters per second (m/sec). Q.2: Compare a transverse wave and a longitudinal

wave. Ans: Difference

Transverse wave Longitudinal wave

• In this wave particles of the medium move at right angle to the path of wave.

• This wave is produced

by the rope.

• In this wave particles of the medium move parallel to the path of the wave.

• This wave is produced

by a spring.

Similarity

• Both waves need a medium to produce.


• In both cases, the medium moves to produce wave.

Q.3: Describe loudness and pitch of the sound.

Ans: Loudness describes what you actually hear. It

depends upon the amplitude of the sound waves. A

sound of greater amplitude sounds louder. When you

talk in a normal voice, the amplitude loudness of the

sound is less. But when you shout, the loudness is

greater. The loudness of a sound is measured in units

called decibels (dB).

Different objects have different loudness. For

example, the loudness of traffic sound is 70dB and

that of rustling leaves is 10 dB. Pitch is the highness

or lowness of a sound. It depends upon the frequency

of the sound wave. The higher the frequency, the

higher the pitch is. The pitch of the girl‟s voice is

higher than the pitch of the boy‟s voice.


(a) Audible frequency range

(b) Ultrasound and infrasound

Ans: (a) Audible frequency range

The range of sound frequencies that can be heard by

an animal or human is called audible frequency range.

A healthy human ear can hear sounds of frequencies

from about 20Hz to 20,000 Hz.

(b) Ultrasound and infrasound Sound waves whose frequency is above the normal

human range (20,000 Hz) of hearing are called

ultrasound. Sound waves which have frequencies

below 20Hz are called infrasound. Doctors use

ultrasound to examine the patient internally.


Unit-12

Electricity

Section Review-1

Q.1: What are static electricity and electric current?

Ans: Positive or negative charges on an object are called

static electricity. The flow of electrons through a

conductor is called electric current.

Q.2: What is the difference between an electrical

conductor and an insulator?

Ans:

Electrical Conductor Insulator

1. It allow the current

to pass through.

2. It includes metals

such as iron, silver etc.

1. It does not allow the

current to pass through.

2. It includes rubber, glass,

sand etc.

Q.3: Define a circuit.

Ans: A complete path, along which electrons can flow, is

called a circuit.

Q.4: How many parts does a circuit consist of?

Ans: It consists of source of electrical energy, connecting

metal wires and device that is run by electrical

energy.

Q.5: What happens to the bulbs in a series circuit if one

of the bulbs burns out?

Ans: The bulbs will become dim.

Q.6: Which circuit would you like to be in your house, a

series or a parallel?

Ans: We would like a parallel circuit to be in the house.

Section Review-2

Q.1: What is potential difference?

Ans: The difference of electric potential between to places

due to which the electrons move through the

conductor is called potential difference.


Q.2: State Ohm’s Law.

Ans: Ohm‟s Law states that, resistance is equal to the

voltage divided by the current.

VR =

I

Q.3: How are resistance, voltage, and electric current

related?

Ans: They are related as

V(voltage)R(Resistance) =

I(current)

Q.4: Find the power produced by 1.8 ampere current at

a voltage of 120V.

Ans: As we know that;

P = V × I

So, P = 120 × 1.8

P= 216Watt

Q.5: Define kilowatt hour.

Ans: One kilowatt hour (KWh) is the amount of energy

used up when an electrical appliance of 1,000 watt

works for 1 hour.

Q.6: What are mains?

Ans: In electricity meters, two wires enter. The wire

through which current flows, are called mains.

Q.7: What is the function of an ELCB?

Ans: It protects the electric circuit from damage due to

overload. It acts as a circuit breaker.

Chapter Review



correct.

earth wires Ohm Killowatt-hour ampere

volts series circuit electrical power

electric current


1. In a series circuit, there is only one path for the

current to flow.

2. One Ohm is the resistance of a wire when 1

ampere current flows across it under 1 Volt

voltage.

3. One Kilowatt-hour is the one unit on our

electricity meter.

4. Watt is the unit for electrical power.

5. The flow of electrons through a conductor is

called electric current.

6. Potential difference is measured in volts.

7. Earth wires protect people from electric shocks.

8. The unit for electric current is ampere.


1. When there are several paths for a current to take,

the circuit is called:

(a) series circuit (b) parallel circuit

(c) incomplete circuit (d) full circuit

2. When current flows through a solution, it can

break up the solution into components.This

process is called:

(a) hydrolysis (b) regeneration (c) electrolysis (d) electrolytes 3. The difference of potential between two places is

measured in: (a) watts (b) amperes (c) volts (d) coulombs 4. “The resistance is equal to the voltage divided by

the current”. This law was presented by: (a) George Ohm (b) George Samual (c) Alssandro Volta (d) James Watt 5. A resistance changes the electrical energy into: (a) chemical energy (b) heat (c) sound (d) nuclear energy 6. The device to measure potential difference in a

circuit is called: (a) ammeter (b) voltmeter (c) barometer (d) thermometer 7. Copper, aluminum, silver, and iron are:


(a) insulators (b) conductors

(c) potential differences (d) wet cells

8. The energy source can be:

(a) a battery (b) a light bulb

(c) a metal wire (d) an electric motor

9. The electrical energy used in our house is

measured in units of:

(a) Kilowatt-hours (b) amperes

(c) Kilowatts (d) watt-hours


Q.1: Describe series and parallel circuits, disadvantages

of a series circuit and advantages of a parallel

circuit.

Ans: When all the parts of an electric circuit are connected

one after the other, the circuit is called a series circuit.

It has only one path for the flow of current.

In series circuit a break in any part of circuit stops the

flow of current in whole circuit. Light bulbs in the

series circuit become dim as more bulbs are added.

When different parts of a circuit are on separate

branches, the circuit is called parallel circuit. It has

more than one path for the flow of current.

Q.2: Explain the heating and chemical effects of the

current.

Ans: When electric current flows through a metal wire.

Then vibration of atoms in wire increases. The wires

become hot by these vibrations. It means electric

current can produce heat. Iron, bulb, electric kettle

etc. get hot by this heating effect.

When current flows through a solution, it can

break up the solution into its components. It is a

chemical effect. Water can be broken down into

oxygen and hydrogen by passing an electric current

through it.

Q.3: How do electrons flow? Explain.

Ans: Current flows from places of higher electric potential

to the lower electric potential. A battery has higher

electric potential on the negative (–ve) terminal and


lower electric potential on the positive (+ve) terminal.

The difference of electric potential between two

places is called potential difference. Potential

difference causes the electrons to move through the

conductor. The greater the potential difference across

a conductor, the greater is the flow of electrons.

Q.4: Write notes on:

i. Resistance ii. Electric Power

iii. MCBs iv. ELCB

Ans: i. Resistance

The tendency of a material to oppose the flow of an

electric current is called its resistance. Resistance of a

wire depends on length of wire, thickness of wire and

type of material.

ii. Electric Power Electric power is the rate at which a device converts

electrical energy into another form of energy. It can

be calculated by multiplying current by the voltage.

Power = voltage × current

P = v × I

iii. MCBs (Miniature Circuit Breakers) An MCB is a small electromagnetic switch that works

like a fuse but it does not blow. It breaks the circuit

by tripping when a current more than its rating flows

through it.

iv. ELCB (Earth Leakage Circuit Breaker) It is a safety device used in electric installations with

high earth impedance to prevent a shock. It quickly

turns off the power when current flowing through the

earth wire exceeds a limit.


Unit-13

Exploring the Space

Section Review-1

Q.1: Is a yellow star, such as the sun, hotter or cooler

than an orange star?

Ans: Yes, the yellow star, such as the sun, is hotter than an

orange star.

Q.2: Where are stars born in the universe?

Ans: The stars are born in the space.

Q.3: What is the earliest stage in the life of a star?

Ans: The earliest stage in the life of a star is nebula.

Q.4: What is supernova?

Ans: The stage in the life of a massive star at which the

light of the star is much more than all other stars of

the galaxy, is called supernova.

Q.5: For how many years will the sun be a red giant?

Ans: The sun will be a red giant for only about 500 million

years.

Q.6: On which factors does the brightness of a star

depend?

Ans: The brightness of the stars depends upon the distance

of the star from the earth and amount of energy the

star emits.

Q.7: What is a light-year?

Ans: The distance that light covers in one year with a speed

of 300,000 kilometers per second.

Section Review-2

Q.1: Define a galaxy.

Ans: A galaxy is a very large group of stars, nebulae,

gases, dust and planets.

Q.2: What is a constellation?

Ans: The clusters of stars with definite patterns are called

constellation.

Q.3: When was Hubble Space Telescope launched?

Ans: It was launched in space on April 24, 1990.


Q.4: Name at least five constellations seen in the sky.

Ans: The Great Bear, Big Dipper, Little Diper, Draco,

Orion.

Q.5: Write briefly about Milky Way galaxy.

Ans: It contains 100 to 200 billion stars. It is 10,000 light-

years thick at centre. Its diameter is about 100,000

light-years.

Q.6: How can you form a sky map?

Ans: We can form a sky map by the help of constellations.

Q.7: What galaxy is our Sun belongs to?

Ans: Our Sun belongs to the Milky Way galaxy

Chapter Review



correct. black dwarf galaxy Milky Way

Hubble Space Telescope

Cassiopeia refracting telescope cosmology

elliptical galaxy

1. Our solar system belongs to the Milky way.

2. An oval-shaped galaxy is called an elliptical

galaxy.

3. Cassiopeia is a constellation.

4. A large group of stars, gas, and dust is a galaxy.

5. The last stage of a low-mass star‟s life is called

black dwarf.

6. A refracting telescope focuses light from a distant

object to a point and magnifies the image.

7. The scientific study of the universe, its origin and

development is called cosmology.

8. The Hubble Space Telescope can see objects in

space more clearly than any other telescope.


1. Star distances are usually measured in:

(a) meters (b) kilometers (c) light-years (d) yards


2. Bright stars may appear dimmer than others because they are:

(a) older (b)farther away (c) younger (d) closer to the earth 3. Polaris (North Star)is in the constellation: (a) Ursa Minor (b) Orion (c) Draco (d) Taurus 4. The most common chemical element in a star is: (a) oxygen (b) carbon (c) sodium (d) hydrogen 5. Betelgeuse is a: (a) red star (b) yellow star (c) blue star (d) orange star 6. When hydrogen atoms fuse to form helium and

great amounts of energy is produced in a protostar, then a protostar is called:

(a) a supergiant (b)a star (c) a neutron star (d) a black hole 7. Galaxies with no special shape or form are

classified as: (a) spiral galaxies

(b) elliptical galaxies (c) rectangular galaxies

(d)irregular galaxies 8. Which constellation is seen as a mighty hunter? (a) Draco (b) Leo (c) Orion (d) Cepheus 9. People have used a star to find the direction: (a) Polaris (b) Lyra (c) Antares (d) Regulus 10. Our neighbouring galaxy is named as: (a) Cepheus (b) Andromeda (c) Canis Major (d) Taurus

Answer the following questions in detail. Q.1: Explain the Big Bang theory of the origin of the

universe. Ans: The Big Bang Theory was first proposed by George

Lamaitre in 1927. About 10 to 20 billion years ago,

the universe was packed into one giant fireball. Then

an explosion started the expansion of the universe.


This explosion is called as the Big Bang. After Big

Bang, the universe changed into the form of hot

clouds. The particles of matter became stars and

galaxies. Since the Big Bang, the universe has been

continuously expanding.

Q.2: Describe the life cycle of a low-mass star. Ans: In space, there are great clouds of hydrogen gas and

dust. Each of these clouds is called a nebula. During travel, nebula collects more dust and gas and changes into a packed hot ball, which releases heat. Such a hot ball is called a protoster. Then, when hydrogen atoms fuse to form helium greater energy is released. At this stage a protostar is called star. The energy of the sun is releasing continuously. The sun will start to collapse and will swell up. It will become a red giant. When the red giant will cool, it will become white dwarf. At last stages the sun will become a dense matter. This last stage is called black dwarf.

Q.3: Describe the three main types of galaxies. Ans: Spiral, Elliptical and Irregular galaxies: Spiral galaxy is a flat disk like with a bulge in the

centre. It has large amount of dust and gases. The Milky Way and Andromda are spiral galaxies.

The oval shaped (football shaped) galaxies are elliptical galaxies. They have less amounts of dust and gases. Trillions of stars may be present in it. Irregular galaxies have no definite shape. These have many shapes. The clouds of Magellan, is an irregular galaxy.

Q.4: Write notes on: i. A refracting telescope ii. Safety methods to use when observing the sun

Ans: i. A refracting telescope This telescope focuses light from a distant object to a

point and later magnifies the image to form a better

view.

In this, the objective lense focuses the light from a

distant object and eye-piece forms an enlarged image

of the object.

ii. Safety methods to use when observing the sun


• Never view the sun directly with the naked eye.

• You can observe sunspot or solar eclipse by

projecting the image of sun through a telescope on a

cardboard.

• You can observe the sun by using welder‟s glasses or

special Mylar glasses.

• Never use normal sun glasses.


Model Paper (Science 7)

1st term (paper 1) Time Allowed: 2:30 Hours Total Marks: 100

Q.1. Multiple Choice Questions. (25×2)


(a) stem (b) root

(c) leaf (d) flower


(a) seeds (b) cones

(c) pollen grains (d) fruit

3. The _____ contains food for the embryo:

(a) stigma (b) endosperm


4. The _____ is sometimes sticky part of a flower:


(c) ovary (d) stigma

5. Which structure produces eggs in a flower?

(a) stamen (b) petal

(c) ovary (d) style



(c) pollination (d) fertilization




8. Where does the exchange of food, oxygen and wastes

occur?




(a) red blood cells (b) white blood cells





(c) frequent urination (d) chest pain



(a) xylem (b) phloem




called:



13. The cells that contain hemoglobin are:







proteins, fats and carbohydrates?








(a) larynx (b) bronchioles



virus is:


(c) common cold (d) appendictis


19. The rib cage ______ when you exhale.

(a) moves up (b) moves our

(c) moves down (d) stays the same

20. Scientist which discover new stars and other




21. The branch of science which deals with the study of

force, energy and motion of objects is called:




units of:

(a) time (b) volume




(c) Al-Khwarizimi (d) Al-Razi


(a) Charless Darwin (b) Joseph Proust




(c) Stephen Poplawski (d) Walter Hunt

Q.2. Complete each of the following sentences with the

given words. (10)

plasma, alveoli, doctors, seed coat, experiment

1. _______ use medicines and surgical techniques to cure

diseases.

2. _______is the most important part of a scientist‟s work.

3. The grape-like clusters of tiny thin-walled balloons in

lungs are called _______.

4. The liquid part of our body is called _______.


5. The _______ protects a seed.

Q.3. Answer any four questions.

Q1. (a) What is science? (3)

(b) Describe the stages of the scientific method. (7)

Q2. (a) Define digestion. (3)

(b) Explain the respiratory system of humans. (7)

Q3. (a) On which surface of leaf more stomata are

present? (3)

(b) Write brief notes on: (7)

i. Transpiration ii. Translocation

iii. Diabetes iv. Asthma

Q4. (a) Why do we eat fruits? (3)

(b) Describe the structure of a seed. (7)

Q5. (a) Which are main branches of science? Define

chemistry. (3)

(b) Write a detail note on pollination in plants. (7)

Q6. (a) What was the name of the inventor of ball point

pen? (3)

(b) Explain fertilization in plants. (7)












their behaviours?
















(a) milk (b) meat

(c) grains (d) eggs

9. When you inhale, your _____ contract (s) and moves

(s) down.




10. Exchange of gases occurs between the ______ and

capillaries.




virus is:




(a) digest food

(b) dissolve bone


(d) carry oxygen





(a) obesity











called:








(a) fruit (b) wind



(a) seeds (b) cones




(c) birds (d) insects

21. The ________ contains food for the embryo:




(a) root hairs (b) radicles

(c) plumules (d) cotyledons





(a) produce ovules (b) attract pollinators

(c) protect the flower bud

(d) produce pollen grains





given words. (10)

pancreas, amino acids, conclusion, ovules, wind

1. Most grasses depend upon _______ for their

pollination.

2. Ovary contains _______which develop into seeds.


3. Diabetes is a disorder of _______.

4. Proteins change into _______ during their digestion.

5. On the basis of analysis of the recorded data, a scientist

comes to a _______.


Q1. (a) Write the stages of the scientific method. (3)

(b) Write contributions of the following scientists. (7)

i. Musa Al-Khwarizmi ii. Madame Curie

Q2. (a) Write a few sources of protein. (3)

(b) Write notes on the following: (7)

i. Breathing process ii. Common cold

Q3. (a) What complications are related to diabetes? (3)

(b) Describe that structure of a plant‟s root permits the

movement of materials. (7)

Q4. (a) Define fertilization. (3)

(b) Write a note on fruit. (7)

Q5. (a) Where does digested food absorb in our blood? (3)

(b) Describe the structure of human heart. (7)

Q6. (a) Name the parts of blood. (3)







(a) stem (b) root

(c) leaf (d) flower








(a) produce ovules (b) attract pollinators





(c) ovary (d) style





occur?




(a) digest food (b) dissolve bone


(d) carry oxygen



(a) obesity (b) high blood pressure
















proteins, fats, and carbohydrates?




(a) milk (b) meat

(c) grains (d) eggs





16. When you inhale, your ____ contract (s) and moves

(s) down.




(a) larynx (b) bronchioles




capillaries.



19. The rib cage ____ when you exhale.


















their behaviours?




units of:

(a) time (b) volume



given words. (10)

peristalsis, larynx, pollinate, hypothesis, herbaceous

1. A _______ provides direction to a scientific project.


2. The reverse process of _______ is called vomiting.

3. _______ is the upper part of a windpipe in our throat.

4. Some plants have woody stems, others have____stems.

5. A bee can help _______ a flower.


Q1. (a) Who is the founder of Modern Algebra? (3)

(b) Write briefly about the measurement of time,

length, mass temperature and volume. (7)

Q2. (a) What is diarrhea? (3)

(b) Describe the digestion of carbohydrates and

proteins. (7)

Q3. (a) What is transpiration? (3)

(b) List and describe the four components of blood and

their functions. (7)

Q4. (a) What is pollination? (3)


Q5. (a) Write few sources of carbohydrates. (3)



Q6. (a) What causes air to move in and out of the lungs?(3)

(b) Explain the respiratory system of humans. (7)













units of:

(a) time (b) volume

























11. When you inhale, your _____ contract (s) and moves

(s) down.




capillaries.




virus is:



14. The rib cage ____ when you exhale.



















called:







(a) fruit (b) wind













(c) ovary (d) style


given words. (10)

phloem, duodenum, calculation, plumule, gametes

1. In sexual reproduction male and female _______ fuse

to form zygote.

2. _______ of the embryo develops into seeds.

3. The food is transported in a plant body through _____.

4. The first part of small intestine is called _______.

5. A mathematician uses the method of _______ to solve

problems.



Q1. (a) Define the unit. What is the unit of mass? (3)

(b) Describe different stages of the scientific method.

(7)

Q2. (a) What is respiration? (3)

(b) Explain the process of digestion of food in the

mouth and the stomach. (7)

Q3. (a) What is asthma? (3)

(b) Describe the structure of human heart. (7)

Q4. (a) Which is the most important part of a seed? (3)

(b) Write a detailed note on pollination in plants. (7)

Q5. (a) How many kinds of teeth are present in our mouth?

(3)


i. Transpiration ii. Translocation

iii. Diabetes iv. Asthma

Q6. (a) What do engineers do? (3)




2nd term (paper 1) Time Allowed: 2:30 Hours Total Marks: 100









(d) melting of rice

3. A factor that can change the environment quickly is:

(a) rain (b) humidity

(c) an earth quake (d) sunlight


(a) rusts (b) burns

(c) decays (d) condenses






(a) Teflon

(b) polyvinyle chloride (PVC)

(c) polypropylene (PP)

(d) polystyrene (PS)






8. In the chemical formula CO2, the subscript 2 shows

which of the following?









by:



11. The atomic number of fluorine (F) is 9. Its mass

number is 19. How many neutrons are present in its

atom?

(a) 7 (b) 8

(c) 9 (d) 10

12. The number of electron in N-shell can be:

(a) 2 (b) 8

(c) 18 (d) 32

13. About ______ of our body is water.

(a) 50% (b) 70%

(c) 80% (d) 90%

14. Shortage of water in the body may cause a disease:

(a) asthma (b) high blood pressure

(c) arthritis (d) all of them

15. A hole in the ground from which water is forced to

the surface by natural pressure is called the:



16. Running water collects in large, deep depressions in

the earth’s crust and forms:





(a) human wastes

(b) industrial wastes

(c) agriculture chemicals

(d) all of them







(a) 10% (b) 14%

(c) 20% (d) 45%

20. The study of interactions between living organisms

and their non-living environment is called:



21. The non-living part of any ecosystem is called the:






23. A great variety of plants and animals is found in a:

(a) desert habitat

(b) pond habitat



24. Seals, penguins and turtles use ____ to move in

water.



(c) tub feet (d) flippers

25. One plant has floating leaves and submerged roots:




given words. (10)

noble gases, chemical change, producers, community,

river

1. Plants use solar energy to make food so, they are

_______.

2. A _______ has many populations in it.

3. A _______ is a large natural stream.

4. Helium (He), neon (Ne), argon (Ar), Krypton (Kr), etc

are _______.

5. Burning of paper is a _______.


Q1. (a) What is a habitat? (3)

(b) Describe factors that can bring daily and yearly

changes in habitat. (7)

Q2. (a) Define geysers. (3)

(b) What makes our water impure? (7)

Q3. (a) Define Valency. (3)

(b) Define the term isotope. Write about the

applications of isotopes in the fields of medicine

and agriculture. (7)

Q4. (a) What is LPG? (3)

(b) Explain with examples that a chemical change

brings change in the properties of a substance. (7)

Q5. (a) What is camouflage? (3)

(b) State the Law of Constant Composition and give

examples.

Q6. (a) Define hydrocarbons. (3)

(b) Write steps of drinking water treatment. (7)





1. Most organisms are active at temperatures between:

(a) 0°C and 10°C (b) 30°C and 60°C

(c) –1°C And 20°C (d) 0°C and 45°C



(c) grazers (d) predators

3. Seals, penguins and turtles use ______ to move in

water.








property is called:




(a) producers (b) scavengers







the earth's crust and forms:




9. Places where ground water bubbles or flows out of

cracks in the rocks automatically are called:




(a) human wastes (b) industrial waves

(c) agricultural chemicals

(d) all of them







to water during:



13. An atom has no overall charge if it contains equal

number of:

(a) electrons and neutrons

(b) electrons and protons

(c) protons and neutrons

(d) positrons and neutrons



charge?
















is:

(a) CaCl (b) Ca2Cl




atom?

(a) 7 (b) 8

(c) 9 (d) 10








(d) melting of ice






(c) an earth quake (d) sunlight


(a) rusts (b) burns






25. The vegetables oil is changed into banaspati ghee





given words. (10)

neutron, water, freezing cold, corrode, health

1. Metal statues ______ very slowly.

2. A ______ is the particle with no charge.

3. Society is rapidly becoming more ______ conscious.

4. A coniferous forest is found in ______ environment.

5. ______ is essential for life.


Q1. (a) What is predation? (3)

(b) Describe adaptations of some aquatic animals to

live in their habitat. (7)

Q2. (a) Define water pollution. (3)

(b) Explain, how water is the most essential element of

life. (7)

Q3. (a) Why atoms are neutral? (3)

(b) Describe the structure of an atom. (7)

Q4. (a) Define a chemical change. (3)

(b) Discuss advantages and harmful effects of chemical

fertilizers. (7)

Q5. (a) Define adaptation. (3)

(b) Explain a food chain and a food web with

examples. (7)

Q6. (a) Write three uses of isotopes in medicines. (3)


i. Plastics

ii. Change of vegetables oil into fat



















(a) teflon (b) polyvinyle chloride (PVC)

(c) Polypropylene (PP) (d) polystyrene (PS)


(a) rotting of an egg

(b) mixing of salt in water









charge?







is:

(a) CaCl (b) Ca2Cl




atom?

(a) 7 (b) 8

(c) 9 (d) 10


by:



12. Whose Statement is this?

"When electrons jump from one shell to the other,

energy is absorbed or evolved."



13. About _____ of our body is water.

(a) 50% (b) 70%

(c) 80% (d) 90%



(c) arthrities (d) all of them










to water during:




(a) 10% (b) 14%

(c) 20% (d) 45%












(a) desert habitat

(b) pond habitat



23. Most organisms are active at temperature between:

(a) 0°C and 10°C (b) 30°C and 60°C

(c) –1°C And 20°C (d) 0°C and 45°C



(c) grazer (d) predators






given words. (10)

polymer, bacteria, configuration, competition, anion

1. ______ may result in change of size of some population

in a habitat.

2. Oxygen of air, and sunlight can kill many ______ in

water.

3. Negatively charged ion is called ______.

4. ______ is the distribution of elements in different

shells.

5. Synthetic rubber is also a ______.


Q1. (a) Define humidity. (3)

(b) Explain a food chain and a food web with

examples. (7)

Q2. (a) What is a glacier. (3)

(b) Write steps of drinking-water treatment. (7)

Q3. (a) Define a molecule and an ion. (3)

(b) State The Law of Constant Composition and give

examples. (7)

Q4. (a) What is a polymer? (3)

(b) Explain reversible and non-reversible change with

examples. (7)

Q5. (a) What is a parasite? (3)

(b) Describe adaptations of some aquatic animals to


Q6. (a) What do you mean by soft and hard water? (3)

(b) How can we preserve water? (7)









(a) desert habitat

(b) pond habitat



3. Most organisms are active at temperature between:

(a) 0°C and 10°C (b) 30°C and 60°C

(c) –1°C And 20°C (d) 0°C and 45°C



(c) grazer (d) predators



property is called:























(a) human wastes (b) industrial waves


(d) all of them










is:

(a) CaCl (b) Ca2Cl




atom?

(a) 7 (b) 8

(c) 9 (d) 10


by:




17. Whose Statement is this?

"When electrons jump from one shell to the other,

energy is absorbed or evolved."




(a) 2 (b) 8

(c) 18 (d) 32






(c) reversible (d) sudden change


(a) rusts (b) burns











(c) polypropylene (PP) (d) polystyrene (PS)


(a) rotting of an egg (b) mixing of salt in water





given words. (10)

atomic number, pollutants, oil refinery, change, water

1. Petroleum is processed in an ______ to obtain useful

products.

2. Our growing is also a process of ______.

3. The number of protons in an atom is called ______.

4. Harmful and unwanted substances in water are called

______.

5. ______ is essential for life.


Q1. (a) Define an ecosystem. (3)


i. Grassland


Q2. (a) What is an iceberg? (3)

(b) How can we preserve water? (7)

Q3. (a) In what part of an atom is most of its mass located?

(3)

(b) What is an ion? How ions are formed? (7)

Q4. (a) Define non-reversible change. (3)


i. Plastics

ii. Change of vegetables oil into fat.

Q5. (a) In which habitat more organisms are found? (3)

(b) Explain how water is the most essential element of

life. (7)

Q6. (a) What do you mean by artisan well? (3)





3rd term (paper 1) Time Allowed: 2:30 Hours Total Marks: 100



(a) metres (b) kilometres

(c) light-years (d) yards

2. Polaris (North Star) is in the constellation:

(a) Ursa Minor (b) Orion

(c) Draco (d) Taurus

3. Betelgeuse is a:

(a) red star (b) yellow star

(c) blue star (d) orange star

4. Galaxies with no special shape or form are classified

as:

(a) spiral galaxies (b) elliptical galaxies

(c) rectangular galaxies (d) irregular galaxies

5. Which constellation is seen as a mighty hunter?

(a) Draco (b) Leo

(c) Orion (d) Cepheus

6. When current flows through a solution, it can break

up the solution into in components. This process is

called:

(a) hydrolysis (b) regeneration

(c) electrolysis (d) electrolytes

7. “The resistance is equal to the voltage divided by the

current”. This law was presented by:

(a) George Ohm (b) George Samual

(c) Alessandro Volta (d) James Watt

8. A resistance changes the electrical energy into:

(a) chemical energy (b) heat

(c) sound (d) nuclear energy


9. The device to measure potential difference in a

circuit is called”

(a) ammeter (b) voltmeter

(c) barometer (d) thermometer




11. A wave carries:

(a) energy (b) matter

(c) water (d) air

12. In a given medium, if the frequency of a wave

increases, its:

(a) wavelength increases

(b) speed increases (c) amplitude decreases

(d) wavelength decreases

13. A sound wave is a:

(a) transverse wave (b) longitudinal wave

(c) reverse wave (d) standing wave

14. Hitting an object harder will make the volume:

(a) softer (b) the same

(c) lower (d) louder

15. The lowest parts of a transverse wave are called:

(a) crests (b) compressions

(c) rarefactions (d) troughs

16. Refractive index of glass is:

(a) 1.47 (b) 2.42

(c) 1.5 (d) 1.33

17. What causes a rainbow?

(a) coloured light (b) absorbed light

(c) artificial light (d) refracted light

18. We see mirage due to the:

(a) reflection of light (b) total internal reflection

(c) dispersion of light (d) spectrum of light


19. Uses the phenomenon of total internal reflection:

(a) camera (b) optical fiber

(c) microscope (d) refracting telescope

20. By mixing magenta and cyan pigments we can

produce the colour:

(a) blue (b) green

(c) white (d) red

21. Heat energy travels through a metal spoon in hot tea

mostly by:

(a) radiation (b) conduction

(c) convection (d) insulation

22. Energy travels from the sun to the earth by:



23. What is the name given to any material that

transfers heat energy easily?

(a) thermal (b) metal

(c) insulator (d) conductor

24. Land and sea breezes blow due to:

(a) conduction of heat (b) convection of heat

(c) radiation of heat (d) emission of heat

25. How is the transfer of heat slowed down in a

thermos bottle?

(a) by the use of a vacuum

(b) by the use of paper

(c) by the use of a metal sheet

(d) by the use of wood


given words. (10)

electric current, convection, incident ray, cosmology,

speed


development is called ______.


2. The flow of electrons through a conductor is called

______.

3. The distance a wave covers or travels in one second is

called its ______.

4. The light ray that enters the new medium, is called an

______.

5. ______ takes place more readily in gases than in

liquids.


Q1. (a) What is convection current? (3)


i. Land and sea breezes

ii. Gliding flight of birds

Q2. (a) Define the dispersion of light. (3)

(b) Verify the “Law of Refraction” through an activity.

(7)

Q3. (a) Define a wave. (3)

(b) Describe loudness and pitch of the sound. (7)

Q4. (a) How many parts does a circuit consist of? (3)

(b) Explain heating and chemical effects of the current.

(7)

Q5. (a) What is a constellation? (3)

(b) Explain the Big Bang theory of the origin of the

universe. (7)

Q6. (a) What are static electricity and electric current? (3)

(b) Write notes on: (7)

i. A refracting telescope






1. When a pot of water is put on a hot stove, the water

at the top gets warm mostly by:



2. What happens if two objects at different

temperatures are touching?

(a) Heat energy transfers from the warmer object.

(b) Heat energy transfers from the cooler object.

(c) Heat energy transfers to the warmer object .

(d) No heat energy transfer takes place.

3. Which one is an insulator of heat?

(a) air (b) mercury

(c) silver (d) iron

4. Which colour is a good reflector of heat?

(a) red (b) black

(c) blue (d) white

5. What type of energy transfer does produce weather?

(a) radiation (b) convection

(c) conduction (d) atmospheric

6. When a light ray passes from one medium to

another at an angle:

(a) reflection occurs

(b) refraction occurs

(c) refraction does not occur

(d) reflection does not occur

7. The splitting of white light into its component

colours is called:

(a) dispersion of light (b) reflection of light


(c) interference of light (d) irregular reflection

8. The separate colours of white light are called the:

(a) spectrum of light (b) group of colours

(c) band of light (d) dispersion of light

9. Which of the following is not a primary colour of

light?

(a) red (b) green

(c) blue (d) yellow



(a) black (b) red

(c) green (d) white

11. The distance between one crest and the next crest is

the wave’s:

(a) amplitude (b) wavelength

(c) frequency (d) speed

12. Hertz is the unit of:


(c) speed (d) frequency

13. Sound waves of frequency less than 20Hz are called:

(a) ultrasound (b) infra sound

(c) ultraviolet waves (d) infrared waves

14. Objects that vibrate slowly have a pitch that is:

(a) high (b) loud

(c) soft (d) low

15. Sound waves travel most quickly through:

(a) solids (b) gases

(c) air (d) liquids






17. The difference of potential between two places is

measured in:

(a) watts (b) amperes

(c) volts (d) coulombs




19. Copper, aluminum, silver and iron are:

(a) insulators (b) conductors

(c) potential differences (d) wet cells

20. The electrical energy used in our houses is measured

in units of:

(a) kilowatt-hours (b) amperes

(c) kilowatts (d) watt-hours

21. Bright stars may appear dimmer than others

because they are:

(a) older (b) farther away

(c) younger (d) closer to the earth

22. The most common chemical element in a star is:

(a) oxygen (b) carbon

(c) sodium (d) hydrogen

23. When hydrogen atoms fuse to form helium and

great amounts of energy is produced in a protostar,

then a protostar is called:

(a) a supergiant (b) a star

(c) a neutron star (d) a black hole

24. People have used a star to find the direction:

(a) Polaris (b) Lyra

(c) Antares (d) Regulus

25. Our neighbouring galaxy is named as:

(a) Cepheus (b) Andromeda

(c) Canis Major (d) Taurus



given words. (10)

refractive index, galaxy, ohm, heat energy, vibration

1. Radiation is the fastest way to transfer ______.

2. ______ is the ratio of the speed of light in vacuum to its

speed in another medium.

3. A ______is a repeated to-and-fro or up-and-down

motion.

4. One ______ is the resistance of a wire when I ampere

current flows across it under IV voltage.

5. A large group of stars, gas and dust is a ______.


Q1. (a) Name four poor conductors of heat. (3)

(b) What is convection? How does it occur? (7)

Q2. (a) What is refractive index? (3)

(b) What is the total internal reflection? Explain it with

an example. (7)

Q3. (a) List the four basic properties of waves. (3)


i. Audible frequency range

ii. Ultrasound and infrasound

Q4. (a) Define circuit. (3)


i. Resistance ii. Electrical power

iii. MCBs iv. ELCB

Q5. (a) Define a galaxy. (3)

(b) Describe the life cycle of the sun-a low mass star.

(7)

Q6. (a) What is the function of an ELCB? (3)

(b) Verify the “Laws of Refraction” through an

activity. (7)






(a) metres (b) kilometres



because they are:



3. Betelgeuse is a:

(a) red star (b) yellow star

(c) blue star (d) orange star

4. When hydrogen atoms fuse to form helium and

great amounts of energy is produced in a protostar,

then a protostar is called:

(a) a supergiant (b) a star

(c) a neutron star (d) a black hole

5. Galaxies with no special shape or form are classified

as:

(a) spiral galaxies (b) elliptical galaxies

(c) rectangular galaxies (d) irregular galaxies







called:








circuit is called”



10. Copper, aluminum, silver and iron are:

(a) insulators

(b) conductors

(c) potential differences

(d) wet cells

11. A wave carries:


(c) water (d) air

12. The distance between one crest and the next crest is

the wave's:


(c) frequency (d) speed




14. Sound waves off frequency less than 20Hz are

called:

(a) ultrasound (b) infra sound

(c) ultraviolet waves (d) infrared waves

15. Hitting an object harder will make the volume:

(a) softer (b) the same

(c) lower (d) louder




(b) refraction occur





(a) 1.47 (b) 2.42

(c) 1.5 (d) 1.33




19. We see a mirage due to the:




light?

(a) red (b) green

(c) blue (d) yellow


mostly by:



22. When a pot of water is put on a hot stove, the water

at the top gets warm mostly by:







24. Which one is an insulator of heat?

(a) air (b) mercury

(c) silver (d) iron

25. Land and sea breezes blow due to:

(a) conduction of heat (b) convection of heat

(c) radiation of heat (d) emission of heat



given words. (10)

siren, mirage, free electrons, Cassiopeia, series circuit

1. ______ is a constellation.

2. In a ______, there is only one path for the current to

flow.

3. A ______ warns us about the danger.

4. A ______ is an optical illusion.

5. Metals have ______ that make better heat conduction.


Q1. (a) When you sit beside a fire, how does heat reach

you? (3)

(b) Write everyday applications of conduction of heat.

(7)

Q2. (a) What is meant by total internal reflection? (3)

(b) What is dispersion of light? Why does white light

get dispersed? (7)

Q3. (a) Define ultrasound and infrasound. (3)

(b) Describe the basic properties of waves. (7)

Q4. (a) Define kilowatt hour. (3)

(b) How do electrons flow? Explain. (7)

Q5. (a) Where are stars born in the universe? (3)

(b) Describe the three main types of galaxies. (7)

Q6. (a) For how many years will the sun be a red giant? (3)

(b) What is convection? How does it occur?








2. What happens if two objects at different

temperatures are touching?

(a) Heat energy transfers from the warmer object.

(b) Heat energy transfers from the cooler object.

(c) Heat energy transfers to the warmer object .

(d) No heat energy transfer takes place.

3. Which colour is a good reflector of heat?

(a) red (b) black

(c) blue (d) white

4. What type of energy transfer does produce weather?

(a) radiation (b) convection

(c) conduction (d) atmospheric

5. How is the transfer of heat slowed down in a

thermos bottle?

(a) by the use of a vacuum

(b) by the use of paper

(c) by the use of a metal sheet

(d) by the use of wood


colours is called:








(a) camera (b) optical fiber




(a) black (b) red

(c) green (d) white

10. By mixing magenta and cyan pigments we can

produce the colour:

(a) blue (b) green

(c) white (d) red


increases, its:


(b) speed increases

(c) amplitude decreases


12. Hertz is the unit of:


(c) speed (d) frequency

13. Objects that vibrate slowly have a pitch that is:

(a) high (b) loud

(c) soft (d) low

14. The lowest parts of a transverse wave are called:

(a) crests (b) compressions

(c) rarefactions (d) troughs

15. Sound waves travel most quickly through:

(a) solids (b) gases

(c) air (d) liquids


up the solution into components. This process is

called:





measured is:



18. “The resistance is equal to the voltage divided by the

current”. This law was presented by:






20. The electrical energy used in our houses is measured

in units of:

(a) kilowatt-hours (b) amperes

(c) kilowatts (d) watt-hours


because they are:



22. The most common chemical element in a star is:

(a) oxygen (b) carbon

(c) sodium (d) hydrogen

23. Which constellation is seen as a mighty hunter?

(a) Draco (b) Leo

(c) Orion (d) Cepheus

24. People have used a star to find the direction:

(a) Polaris (b) Lyra

(c) Antares (d) Regulus

25. Our neighbouring galaxy is named as:

(a) Cepheus (b) Andromeda

(c) Canis Major (d) Taurus



given words. (10)

prison, vocal cords, earth wires, insulators, Milky way

1. Woollen clothes and blankets are ______ that slow the

transfer of heat out of our body.

2. A ______ is a transparent wedge-shaped block of glass.

3. When we speak or sing, the ______ in our throat

vibrate.

4. ______ protect people from electric shocks.

5. Our solar system belongs to the ______.


Q1. (a) What is conduction of heat? (3)

(b) Write a note on a thermos bottle. (7)

Q2. (a) What are the primary pigment colours? (3)

(b) Verify the "Laws of Refraction" through an activity.

(7)

Q3. (a) What is the relationship between frequency and

pitch. (3)

(b) Compare a transverse wave and a longitudinal

wave. (7)

Q4. (a) State Ohm's Law. (3)

(b) Describe series and parallel circuits, disadvantages

of a series circuit and advantages of parallel circuit.

(7)

Q5. (a) What is supernova? (3)




Q6. (a) What galaxy is our sun belong to? (3)


universe.



Final term (paper 1) Time Allowed: 2:30 Hours Total Marks: 100


1. Scientists which discover new stars and other









units of:

(a) time (b) volume










(c) Stephen Poplawski (d) Walter Hunt





occur?
















called:

















(a) desert habitat (b) pond habitat




18. Seals, penguins and turtles use ______ to move in

water.







mostly by:










23. A wave carries:


(c) water (d) air


increase, its:


(b) speed increases

(c) amplitude decreases






given words. (10)

Plasma, river, convection, speed, experiment, doctors


1. ______ use medicines and surgical techniques to cure

diseases.

2. ______ is the most important part of a scientist's work.

3. The liquid part of our blood is called ______.

4. ______ takes place more readily in gases than in

liquids.

5. The distance a wave covers or travels in one second is

called its ______.

6. A ______ is a large natural stream.


Q1. (a) What is science? (3)

(b) Describe the stages of the scientific method. (7)

Q2. (a) Why do we eat fruits? (3)

(b) Describe the structure of a seed. (7)

Q3. (a) What is a habitat? (3)



Q4. (a) Define Valency. (3)

(b) Define the term isotope. Write about the

applications of isotopes in the field of medicine and

agriculture. (7)

Q5. (a) What is conduction of heat? (3)

(b) Write a note on thermos bottle. (7)

Q6. (a) What is supernova? (3)




















(a) larynx (b) nasal cavity



virus is:



6. The rib cage ______ when you exhale.




(a) stem (b) root

(c) leaf (d) flower


(a) seeds (b) cones


9. The ______ contains food for the embryo:



(c) pollen grains (d) root

10. The ______ is sometimes sticky part of a flower:





(c) ovary (d) style




13. About _____ of our body is water.

(a) 50% (b) 70%

(c) 80% (d) 90%



(c) arthritis (d) all of them










(a) human wastes (b) industrial wastes


(d) all of them


to water during:





(a) 10% (b) 14%

(c) 20% (d) 45%



called:



21. "The resistance is equal to the voltage divided by

the current". This law was presented by:







circuit is called:




(a) metres (b) kilometre


25. Polaris ( North Star) is in the constellation:

(a) Ursa Minor (b) Orion

(c) Draco (d) Taurus


given words. (10)

electric current, community, alveoli, seed coat,

produces

1. The grape-like clusters of tiny thin-walled balloons in

lungs are called ______.

2. The ______ protects a seed.


3. Plants use solar energy to make food so, they are ____.

4. A ______ has many populations in it.


______.


Q1. (a) Write a few sources of protein. (3)



Q2. (a) Define fertilization. (3)


Q3. (a) What is predation? (3)

(b) Describe adaptations of some acquatic animals to


Q4. (a) Why atoms are neutral? (3)

(b) Describe the structure of an atom. (7)

Q5. (a) What is meant by total internal reflection? (3)

(b) What is dispersion of light? Why does white light

get dispersed? (7)

Q6. (a) Define kilowatt hour? (3)

(b) How do electrons flow? Explain. (7)











3. Who studied plants, animals, microorganisms and

their behaviours?
















occur?













called:


















atom?

(a) 7 (b) 8

(c) 9 (d) 10


by:





(a) 2 (b) 8

(c) 18 (d) 32




(b) refraction occurs




colours is called:







light?

(a) red (b) green

(c) blue (d) yellow



(a) black (b) red

(c) green (d) white






measured in:








given words. (10)

incident ray, electric current, cosmology, conclusion,

noble gases

1. On the basis of analysis of the recorded data, a scientist

comes to a ______.

2. Helium (He), neon (Ne), argon (Ar), krypton (Kr), etc.

are ______.


______.


development is called ______.

5. The light ray that enters the new medium, is called an

______.


Q1. (a) Who is the founder of Modern Algebra? (3)

(b) Write briefly about the measurement of time,

length, mass, temperature and volume. (7)

Q2. (a) What is transpiration? (3)

(b) List and describe the four components of blood and

their functions. (7)

Q3. (a) What is a glacier? (3)

(b) Explain food chain and a food web with examples.

(7)

Q4. (a) Define humidity? (3)

(b) Write steps of drinking water treatment. (7)

Q5. (a) Name four poor conductors of heat. (3)

(b) What is convection? How does it occur? (7)

Q6. (a) Define a circuit. (3)


i. Resistance ii. Electric Power

iii. MCBs iv. ELCB











3. Who produce enzymes for the final digestion of





(a) milk (b) meat

(c) grains (d) eggs

5. When you inhale, your ____ contract (s) and move

(s) down.



6. Exchange of gases occurs between the _____ and

capillaries.




virus is:



8. What helps protect seed?

(a) fruit (b) wind




(a) seeds (b) cones





11. The ________ contains food for the embryo:






13. The ________ is sometimes sticky part of a flower:




(a) produce ovules

(b) attract pollinators







(a) boiling of water (b) evaporation of water

(c) burning of paper (d) melting of ice



(c) an earthquake (d) sunlight


(a) rusts (b) burns









(c) polypropylene (PP) (d) polystyrene (PS)


(a) 1:47 (b) 2:42

(c) 1:5 (d) 1:33




23. We see a mirage due to the:




(a) camera (b) optical fibre


25. By mixing a magenta and cyan pigments we can

produce the colour:

(a) blue (b) green

(c) white (d) red


given words. (10)

herbaceous, chemical change, galaxy, amino acids,

Ohm

1. Proteins change into ______during their digestion.

2. Some plants have woody stems, other have ____ stems.

3. Burning of paper is a ______.

4. One ______ is the resistance of a wire when 1 ampere

current flows across it under IV voltage.

5. A large group of stars, gas and dust is a ______.



Q1. (a) What is respiration? (3)

(b) Explain the process of digestion of food in the

mouth and the stomach. (7)

Q2. (a) Which is the most important part of a seed? (3)

(b) Write a detailed note on pollination in plants. (7)

Q3. (a) Define an ecosystem. (3)


i. Grassland habitat

ii. Effect of humidity on life

Q4. (a) In what part of an atom is most of its mass located?

(3)

(b) What is an ion? How ions are formed? (7)

Q5. (a) What is convection current? (3)


i. Land and sea breezes

ii. Gliding and flight of birds

Q6. (a) What is a constellation? (3)


universe. (7)


Scheme of Study

34 weeks 5/6 days a week Three Terms

1st Term WEEK UNIT # NAME of UNIT PAGE #

Ist 1

WHAT IS SCIENCE? / Science / Science

at Work / Scientific Method / Main

Branches of Science / Measurement in

Science / Contributions of Some

Eminent Muslim Scientists /

Contributions of Some Eminent Non-

Muslim Scientists / Unit Review

5 to 16

2nd 2

DIGESTION and RESPIRATION in

HUMAN: Your Digestive System /

Digestion of Various Kinds of Food /

Digestive Disorders

17 to 26

3rd Revision and Test of the Above Topics

(Units 1 & 2 )

4th " Your Respiratory System / Respiratory

Disorders / Unit Review

27 to 32

5th 3 TRANSPORT IN HUMAN and PLANTS:

Human Blood Circulatory System /

Your Blood / Transplantation

33 & 38

6th Revision and Test of the Above Topics

(Units 2 & 3 )

7th "

Diet Affects your Circulatory System /

Transportation in Plants / The

Structure of Plant Parts Permits the

Movement of Materials / Unit Review

39 to 48

8th 4

PLANT REPRODUCTION: PLANTS /

Types of Reproduction / Flower / How

does a seed develop? / Seeds and

Fruits / Unit Review

49 to 60

9th Revision and Test of the Above Topics

(Units 3 & 4 )

10th Preparatory Tests' Week

11th 1st Term Paper (Units 1 to 4)

2nd Term WEEK UNIT # NAME of UNIT PAGE #


12th 5

LIVING TOGETHER IN AN ENVIRONMENT: Ecosystems / Parts of Ecosystems - Community and Habitat / The Factors Causing Changes in a Habitat

61 to 68

13th "

Adaptations of Organisms to Live in a Particular Habitat / Feeding Relationship in an Ecosystem / Unit Review

69 to 80

14th

Revision and Test of the Above Topics (Unit 5)

15th 6

WATER: Water for Life / Surface Water / Water Beneath the Surface of Earth / How to Bring Ground Water to the Surface?

81 to 89

16th " What Makes our Water Impure? / Cleaning Water / Where do we Use Water? / Unit Review

90 to 98

17th

Revision and Test of the Above Topics (Unit 6 )

18th 7

STRUCTURE OF ATOM: Atoms-Building Blocks of Matter / Structure of An Atom / Atomic and Mass Numbers / Distribution of Electrons in Shells (Electronic Configuration) / Valency - Combining of an Element

99 to 108

19th " Ion / Isotopes / What is a Molecule? / Chemical Formula / Law of Constant Composition / Unit Review

109 to 116

20th

Revision and Test of the Above Topics (Unit 7 )

21st 8

CHANGES and PROCESSES AROUND US: Types of Changes / Changes in the Environment / Applications of Chemical Changes and Processes / Use of Fertilizers in Agriculture / How does Vegetable Oil Change into Fat? / Plastics / Unit Review

117 to 128

22nd

2nd Term Paper (Units 5 to 8)

3rd Term

WEEK UNIT # NAME of UNIT PAGE #

23rd 9 TRANSMISSION OF HEAT: Heat / Conduction / Convection / Radiation

129 to 134

24th " Everyday Applications of Conduction of Heat / Everyday Applications of

135 to 142


Convection Currents / Everyday Applications of Radiation of Heat / The Vacuum Flask / Unit Review

25th Revision and Test of the Above Topics (Unit 9)

26th 10

REFRACTION and DISPERSION of LIGHT: Refraction of Light / Laws of Refraction / Refractive Index / Dispersion of Light / Critical Angle / Applications of Refraction, Dispersion and Total Internal Reflection / Colours of Light / Unit Review

143 to 158

27th 11

WAVES and SOUND: Waves / Types of Waves / Properties of Waves / Properties of Sound / Sound Depends on the Size and Shape of the Instrument / Audible Frequency Range / Unit Review

159 to 172

28th Revision and Test of the Above Topics (Units 10 & 11 )

29th 12 ELECTRICITY: What Electricity can Do? / What is Electricity / Types of Electric Circuits / Electricity and Energy

173 to 182

30th "

How do Electrons Flow? / Electrical Meters / Electric Power / Dangers of Electricity / Safe Use of Electricity / Unit Review

182 to 190

31st Revision and Test of the Above Topics (Unit 12)

32nd 13

EXPLORING the SPACE: The Big Bang Theory / Stars / Life Cycle of a Star - Our Sun / Galaxies and Star Groups / Constellations / Telescopes / Safety Tips For Observing the Sun / Unit Review

191 to 208

33rd Revision and Test of the Above Topics (Unit 13)

34th 3rd Term Paper (Units 1 to 13)

NOTE : Teachers may synchronize this "Scheme of Study"

with our (Term Wise ) "Model Papers", according to

their specific needs.


Scheme of Study

40 weeks 5/6 days a week Four Terms

1st Term WEEK UNIT # NAME of UNIT PAGE #

Ist 1

WHAT IS SCIENCE? / Science / Science at Work / Scientific Method / Main Branches of Science / Measurement in Science / Contributions of Some Eminent Muslim Scientists / Contributions of Some Eminent Non-Muslim Scientists / Unit Review

5 to 16

2nd 2

DIGESTION and RESPIRATION in HUMAN: Your Digestive System / Digestion of Various Kinds of Food / Digestive Disorders

17 to 26

3rd Revision and Test of the Above Topics (Units 1 & 2 )

4th " Your Respiratory System / Respiratory Disorders / Unit Review

27 to 32

5th 3 TRANSPORT IN HUMAN and PLANTS: Human Blood Circulatory System / Your Blood / Transplantation

33 & 38


7th "

Diet Affects your Circulatory System / Transportation in Plants / The Structure of Plant Parts Permits the Movement of Materials / Unit Review

39 to 48

8th 4

PLANT REPRODUCTION: PLANTS / Types of Reproduction / Flower / How does a seed develop? / Seeds and Fruits / Unit Review

49 to 60


10th 1st Term Paper (Units 1 to 4)

2nd Term WEEK UNIT # NAME of UNIT PAGE #

11th 5

LIVING TOGETHER IN AN ENVIRONMENT: Ecosystems / Parts of Ecosystems - Community and Habitat / The Factors Causing Changes in a Habitat

61 to 68


12th "

Adaptations of Organisms to Live in a Particular Habitat / Feeding Relationship in an Ecosystem / Unit Review

69 to 80


14th 6

WATER: Water for Life / Surface Water / Water Beneath the Surface of Earth / How to Bring Ground Water to the Surface?

81 to 89

15th " What Makes our Water Impure? / Cleaning Water / Where do we Use Water? / Unit Review

90 to 98

16th Revision and Test of the Above Topics (Unit 6 )

17th 7

STRUCTURE OF ATOM: Atoms-Building Blocks of Matter / Structure of An Atom / Atomic and Mass Numbers / Distribution of Electrons in Shells (Electronic Configuration) / Valency - Combining of an Element

99 to 108

18th " Ion / Isotopes / What is a Molecule? / Chemical Formula / Law of Constant Composition / Unit Review

109 to 116

19th Revision and Test of the Above Topics (Unit 7 )

20th 2nd Term Paper (Units 5 to 7)

3rd Term WEEK UNIT # NAME of UNIT PAGE #

21st 8

CHANGES and PROCESSES AROUND US: Types of Changes / Changes in the Environment / Applications of Chemical Changes and Processes / Use of Fertilizers in Agriculture / How does Vegetable Oil Change into Fat? / Plastics / Unit Review

117 to 128

22nd 9 TRANSMISSION OF HEAT: Heat / Conduction / Convection / Radiation

129 to 134

23rd "

Everyday Applications of Conduction of Heat / Everyday Applications of Convection Currents / Everyday Applications of Radiation of Heat / The Vacuum Flask / Unit Review

135 to 142



25th 10

REFRACTION and DISPERSION of LIGHT: Refraction of Light / Laws of Refraction / Refractive Index / Dispersion of Light / Critical Angle / Applications of Refraction, Dispersion and Total Internal Reflection / Colours of Light / Unit Review

143 to 158

26th 11

WAVES and SOUND: Waves / Types of Waves / Properties of Waves / Properties of Sound / Sound Depends on the Size and Shape of the Instrument / Audible Frequency Range / Unit Review

159 to 172


28th 12 ELECTRICITY: What Electricity can Do? / What is Electricity / Types of Electric Circuits / Electricity and Energy

173 to 182


30th 3rd Term Paper (Units 9 to 12)

4th Term WEEK UNIT # NAME of UNIT PAGE #

31st 12 Contd…

How do Electrons Flow? / Electrical Meters / Electric Power / Dangers of Electricity / Safe Use of Electricity / Unit Review

182 to 190

32nd 13

EXPLORING the SPACE: The Big Bang Theory / Stars / Life Cycle of a Star - Our Sun / Galaxies and Star Groups / Constellations / Telescopes / Safety Tips For Observing the Sun / Unit Review

191 to 208

33rd

Revision and Test of the Above Topics (Unit 13)

34th 1st TERM

(REVISION) UNITS 1 to 4 5 to 60

35th 2nd TERM (REVISION)

UNITS 5 to 7 61 to 116

36th 3rd TERM

(REVISION) UNITS 8 to 12

117 to 182


37th 4th TERM

(REVISION) UNITS 12 (Contd…) to 14

182 to 208

38th Preparatory Tests' Week

39th Preparatory Leaves

40th 4th Term Paper (Units 1 to 13)

NOTE : Teachers may synchronize this "Scheme of Study"

with our (Term Wise ) "Model Papers", according to

their specific needs.

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