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CBSE 10th Science 2018-2019

Unsolved Sample Paper II

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CBSE 10th Science 2018-2019

Unsolved Sample Paper II

TIME - 3 HR. | QUESTIONS – 27

General Instructions: Maximum Marks: 80

(i) The question paper comprises of five sections – A, B, C, D and E. You are to attempt all the

sections.

(ii) All questions are compulsory.

(iii) Internal choice is given in sections B, C, D and E.

(iv) Question numbers 1 and 2 in Section-A are one mark questions. They are to be answered in

one word or in one sentence.

(v) Question numbers 3 to 5 in Section- B are two marks questions. These are to be answered in

about 30 words each.

(vi) Question numbers 6 to 15 in Section-C are three marks questions. These are to be answered

in about 50 words each.

(vii) Question numbers 16 to 21 in Section-D are 5 marks questions. These are to be answered in

about 70 words each.

(viii) Question numbers 22 to 27 in Section- E are based on practical skills. Each question is a

two marks question. These are to be answered in brief.

Section – A

Q.1. The Inner lining of the small intestine has numerous finger-like projections called villi.

What is the main function of these villi?

Q.2. Which products are formed when ‘coal’ and ‘petroleum’ are burnt?

Section – B

Q.3. How to prevent iron from the process of rusting? Give two ways.

Q.4. What is difference between pollination and fertilization?

Q.5. Why do we use convex mirrors as rearview mirrors in all vehicles?

OR

A light ray travelling in air enters into water obliquely. Does the light ray bend toward the

normal or away from the normal? Why?

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Section – C

Q.6. Write one equation each for decomposition reaction in which energy is supplied in the form

of heat, light or electricity.

Q.7. (a) Name two constituents of baking powder.

(b) How does baking powder differ from baking soda?

(c) Explain the action of baking powder in the making of cake (or bread). Write the

equation of the reaction involved.

OR

(a) Fresh milk from cows have pH of 6. So how does the pH changes when this milk is

turned to curd?

(b) Why should plaster of Paris be stored in moisture proof container?

(c) (i) Give name of substances after the treatment with chlorine will give bleaching

powder.

(ii) What is the name of the sodium compound that is used to softening hard water?

Q.8. A quiz contest was being held in the school for chemistry students. The quiz-master said:

An element has the electronic configuration 2, 8, 2.

(a) What is the atomic number of this element?

(b) Is it a metal, non-metal or metalloid?

(c) Which of the elements Mg, O, P or Ar shows similarity with this element?

(d) We use a compound of this element in our food. Identify that compound.

(e) A compound of this element causes hardness of water. Identify that compound.

Q.9. List any three plant hormone, along with their physiological effect on the growth

development of plants.

Q.10. What is the role of saliva in the digestion of food?

Q.11. Light, of wavelength of 500 nm in air, enters a glass plate of refractive index 1.5

Find

(i) Speed

(ii) Frequency and

(iii) Wavelength of light in glass.

Assume that the frequency of light remains the same in both media?

OR

The image of an object placed at 40cm in front of a lens is obtained on a screen at a

distance of 100cm from it. Find the focal length of the lens. What would be the

height of the image if the object is 4cm high?

Q.12. Derive the expression for the resistivity of a substance and give the meaning of each

symbol which occurs in it.

Q.13. Define and derive the Joule’s law of heating.




Q.14. (a) Compare and contrast biomass and hydroelectricity as a source of energy.

(b) Hydrogen has been used as a rocket fuel. Do you consider it as a cleaner fuel than CNG?

Why and why not?

Q.15. (a) Show the flow of energy in an ecosystem. State why it is unidirectional?

(b) Write down four daily life activities that are eco-friendly.

OR

Distinguish between biodegradable and non-biodegradable substances.

List two effects of each of them on our environment.

Section – D

Q.16. (a) Give reasons for the following statements below:

(i) Metals replace hydrogen from dilute acids and non-metals do not.

(ii) During the process of extraction, ores of sulphide and carbonate are converted

into oxides.

(b) Why do the surface of few metals have a dull appearance when they are exposed

to air for a long period of time?

(c) Explain why sour substances like lemon or tamarind juice are effective in

cleaning the vessels.

Q.17. (a) Write two points of difference in the structures of diamond and graphite.

(b) Explain why graphite can be used as a lubricant but diamond cannot.

(c) State the two properties of carbon which led to the huge number of carbon

compounds.

(d) Both carbon and silicon belong to Group 14 of the periodic table.

But the tendency to exhibit catenation in carbon is much more than silicon. Explain.

OR

A to F are the structural formulae of some organic compounds:




(a) Which of these compounds represent the same family?

(b) Which of these do not represent any hydrocarbon?

(c) How can compound ‘C’ be converted to compound ‘A’?

(d) How can you differentiate saturated and unsaturated hydrocarbons on the basis

of burning behavior?

Q.18. (a) Write three main steps which take place in the chloroplast during

photosynthesis.

(b) How do stomata open and close?

(c) Which raw material is made available to plants for photosynthesis?

Q.19. (a) How is the study of evolution and classification interlinked?

(b) How is the equal genetic contribution of female and male parents ensured in

the progeny?

(c) What factors could lead to the rise of a new species?

OR

(a) What are fossils? What do they tell us about the process of evolution?

(b) Explain with examples how the following provide evidences in favor of evolution

in organisms.

(i) Homologous organs

(ii) Analogous organs

(iii) Fossils

Q.20. Answer the following:

(a) What according to you happens to the eyes when you enter a darkened room

from bright sunlight?

(b) Suggest how the iris helps protect the retina from damage by bright light.

(c) How do you compare the defect of a person wearing spectacles of +1.5 D to the

one wearing spectacles of −1.5 D?

Q.21. (a) List the three properties of magnetic field lines.

(b) Define electromagnet. State the principle on which the working of magnet is

based.

(c) What are the factors affecting the strength of an electromagnet.

OR

(a) Define magnetic field lines and write their characteristics.

(b) State the direction of magnetic field lines with a neat labelled diagram.

(c) Is the magnetic field same all around a bar magnet? Explain with reasons




Section – E

Q.22. What is the pH of neutral solution at 25°C? Calculate the pH value of 𝟏𝟎−𝟐𝐌 𝐇𝐍𝐎𝟑

solution.

OR

What happens when a sheet of zinc is put in copper sulphate solution?

Q.23. What is meant by the term pH of a solution? The pH values of rainwater collected

from two cities A and B corresponded to 6 and 5. Water of which city is more

acidic?

Q.24. (a) List any two advantages of vegetative propagation.

(b) Diagrammatically explain the process of reproduction in Amoeba.

(c) Where does fertilisation occur in the female reproductive tract?

OR

Observe the figure carefully and answer the questions based on it.

(a) What changes take place in the guard cells?

(b) In an experiment to demonstrate the occurrence of stomata, why is it preferred

to take an epidermal peel from the lower surface of the leaf?

Q.25. What will be the steps to study the different parts of an embryo of pea seed?

Q.26. You are given following current–time graphs from two different sources:




(i) Name the type of current in the two cases.

(ii) Identify any one source for each type of these currents

Q.27. In the glass slab experiment shown below, four students A, B, C and D did the

following:

A. Kept eyes far from the glass slab while placing both pins P3 and P4.

B. Kept eyes close to the glass slab while placing both pins P3 and P4.

C. Kept eyes close to the glass slab while placing pin P3 and far from the slab while

placing pin P4.

D. Kept eyes far from the glass slab while placing pin P3 and close to the slab while

placing pin P4.

The correct procedure is that of student:

(a) A

(b) B

(c) C

(d) D

OR

In an experiment, the image formed by a concave mirror is real and that of the

convex mirror is virtual. What shoulsd be the position of the screen for both

mirrors?




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