CBSE Chemistry IX Matter in our surrounding Chemistry solved questions

Q.1 Camphor disapperars without leaving any residue. Explain?Ans. Camphor disappears without leaving any residue because of sublimation, as it changes its statedirectly from solid to gas without changing to liquid.Q.2 Why do we feel cool when we touch a piece of ice?Ans. We feel cool because the temperature of ice is 0 deg C and our bodys temp is higher than 0 deg C.Q.3 Convert the following:-a) 573 KAns. 573-273= 300 deg Cb) 36 deg CAns. 273+36 = 309 Kc) 373 deg CAns. 373+273= 646 KQ.4 Both the process of evaporation and boiling involves the change of state from liquid to gas but stillthey are different from each other. Justify.Ans. Evaporation is diffeent from boiling as evaporation is a natural phenomenon, occurs on the surfaceof the water and also it is a slow process whereas boiling is an artificial phenomenon , it occurs in the bulkof the liquid and is a fast process.Q.5 Why is Kelvin considered as the best scale for measuring the temperature?Ans. Kelvin is the best scale for measuring the temperature because it has no max temp. and it canmeasure temperature to any extent.Q.6 How can you show that evaporation causes cooling?Ans. When we put some acetone on our hand , after sometime we will feel coolness on our hand becausethe action absorbs kinetic energy from our hand & evaporates and evaporation causes cooling.Q.7 What is the significance of boiling point & melting point of a substance?Ans. The significance of boiling point and melting point is that it shows the purity of the substance.Q.8 When we put CuSO4 in water, after sometime we find the soln. turns blue. Why? Also, on heating it,what change will occur?Ans. The solution turns blue because of diffusion. On heating the solution nothing will happenQ.9 How can you justify that table is a solid?Ans. When we apply force on the table it doesnt change its shape because its intermolecules are tightlypacked , this shows that table is solid.Q.10 Arrange the following in decreasing order of force of attraction: Water, Salt, Oxygen,Also, state the reason.Ans. Salt, Water, OxygenSalt has the maximum force of attraction as it is a solid, followed by water as it is a liquid. Oxygenis a gas so its force of attraction is the least.Q. 11 State characteristics of matter demonstrated by :a) diffusionAns. Diffusion involves movement of different particles so that they become intermixed uniformly .b) Brownian motionAns.It is thwe zig-zag movement of the small particles suspended in a liquid or a gas .Q.12 When an incense stick (agarbatti) is lighted in one corner of a room, its fragrance spreads in thewhole room quickly.Which characteristic of the particles of matter is illustrated by this observation?Ans. Particles of matter are constantly moving.Q.13 The boiling point of alcohol isn 78 deg C. What is this temperature on Kelvin scale?Ans. K= Deg C + 273 = 78 + 273 = 351 KQ. 14 The Kelvin scale temperature is 0 K. What is the corresponding Celsius scale temperature?Ans. 273 deg CQ. 15 What is Latent Heat of Fusion?Ans. The latent heat of fusion (or melting) of a solid is the quanity of heat in joules required to convert 1kilogram of the solid (at its melting point ) to liquid, without any change in temperature.Q. 16 Define latent heat of Vaporisation?Ans. The latent heatm of vaporisation of a liquid is the quantity of heat in joules required to convert 1kilogram of the liquid (at its boiling point ) to vapour or gas, without any change in temperature.

MCQ 9th science Matter In Our Surroundings MCQ1. Camphor is purified by the process of

a. evaporation b. distillation c. sublimation d. filtration

2. LPG is used in the kitchens in our homes in the-

a. Solid form b. compressed form c. gaseous form d. none.

MATER IN OUR SURONDING DEFINATIONSMatter:matter is commonly defined as the substance of which physical objects are composed, not counting the contribution of various energy or force-fields, which are not usually considered to be matter per se (though they may contribute to the mass of objects). Matter constitutes much of the observable universe, although again, light is not ordinarily considered matter. Unfortunately, for scientific purposes, "matter" is somewhat loosely defined. It can also be defined as a physical substance that has mass and volume.

Volume:The volume of a solid object is the three-dimensional concept of how much space it occupies, often quantified numerically. One-dimensional figures (such as lines) and two-dimensional shapes (such as squares) are assigned zero volume in the three-dimensional space.Mass:Mass is a fundamental concept in physics, roughly corresponding to the intuitive idea of "how much matter there is in an object". Mass is a central concept of classical mechanics and related subjects, and there are several definitions of mass within the framework of relativistic kinematics (see mass in special relativity and mass in General Relativity). In the theory of relativity, the quantity invariant mass, which in concept is close to the classical idea of mass, does not vary between single observers in different reference frames

Diffusion:In the second sense of diffusion is the spontaneous net movement of particles from an area of high concentration to an area of low concentration through a semi-permeable membrane. For example, diffusing molecules will move randomly between areas of high and low concentration but because there are more molecules in the high concentration region, more molecules will leave the high concentration region than the low concentration one. Therefore, there will be a net movement of molecules from high to low concentration. Initially, a concentration gradient leaves a smooth decrease in concentration from high to low which will form between the two regions. As time progresses, the gradient will grow increasingly shallow until the concentrations are equalized.

Force:force is what causes a mass to accelerate. It may be experienced as a lift, a push, or a pull. The acceleration of the body is proportional to the vector sum of all forces acting on it (known as net force or resultant force). In an extended body, force may also cause rotation, deformation, or an increase in pressure for the body. Rotational effects are determined by the torques, while deformation and pressure are determined by the stresses that the forces create.

Pressure:Pressure is the force per unit area applied on a surface in a direction perpendicular to that surface.

Density:density is mass (m) per unit volume (V) the ratio of the amount of matter in an object compared to its volume. A small, heavy object, such as a rock or a lump of lead, is denser than a larger object of the same mass, such as a piece of cork or foam.

Kinetic energy:The kinetic energy of an object is the extra energy which it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its current velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes. Negative work of the same magnitude would be required to return the body to a state of rest from that velocity.

Speed:speed is a quantity that measures the ratio of an evolution to time. Example: speed of sedimentation, speed of economic growth, speed of chemical reaction etc.

Melting point:The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. Although the phrase would suggest a specific temperature and is commonly and incorrectly used as such in most textbooks and literature, most crystalline compounds actually melt over a range of a few degrees or less. At the melting point the solid and liquid phase exist in equilibrium. When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point.

Atmospheric pressure:Atmospheric pressure is the pressure at any point in the Earth's atmosphere. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. Low pressure areas have less atmospheric mass above their location, whereas high pressure areas have more atmospheric mass above their location. Similarly, as elevation increases there is less overlying atmospheric mass, so that pressure decreases with increasing elevation. A column of air 1 square inch in cross section, measured from sea level to the top of the atmosphere, would weigh approximately 14.7 lbf. A 1 m (11 sq ft) column of air would weigh about 100 kilonewtons (equivalent to a mass of 10.2 tonnes at the surface).

Latent heat:Latent heat is the amount of energy in the form of heat released or absorbed by a substance during a change of phase (i.e. solid, liquid, or gas), - also called a phase transition.

Vaporisation:Evaporation is the process by which molecules in a liquid state (e.g. water) spontaneously become gaseous (e.g. water vapor). It is the opposite of condensation. Generally, evaporation can be seen by the gradual disappearance of a liquid, when exposed to a significant volume of gas.

Matter in our surrounding notes for class 9thMatter in our surrounding Explanatory notesIntroduction:Everything in this universe is made up of material which scientists have named matter. The air we breathe, the food we eat, stones, clouds, stars, plants and animals, even a small drop of water or a particle of sand each thing is matter.Early Indian philosophers classified matter in the form of five basic elements air, earth, fire, sky and water.Modern day scientists have evolved two types of classification of matter based on their physical properties and chemical nature.Characteristics of Particles of Matter1. PARTICLES OF MATTER HAVE SPACE BETWEEN THEM- when we make tea, coffee or lemonade (nimbu paani ), particles of one type of matter get into the spaces between particles of the other. This shows that there is enough space between particles of matter. Similarly particles of sugar, salt, Dettol, or potassium permanganate get evenly distributed in water.2. PARTICLES OF MATTER ARE CONTINUOUSLY MOVING-Particles of matter are continuously moving, that is, they possess what we call the kinetic energy. As the temperature rises, particles move faster. So, we can say that with increase in temperature the kinetic energy of the particles also increases.3. PARTICLES OF MATTER ATTRACT EACH OTHER-Particles of matter have force acting between them. This force keeps the particles together. The strength of this force of attraction varies from one kind of matter to another.States of Matter1. THESOLIDSTATE-all solids have a definite shape, distinct boundaries and fixed volumes, that is, have negligible compressibility. Solids have a tendency to maintain their shape when subjected to outside force. Solids may break under force but it is difficult to change their shape, so they are rigid.2. THELIQUIDSTATE-Liquids have no fixed shape but have a fixed volume. They take up the shape of the container in which they are kept. Liquids flow and change shape, so they are not rigid but can be called fluid. The rate of diffusion of liquids is higher than that of solids. This is due to the fact that in the liquid state, particles move freely and have greater space between each other as compared to particles in the solid state.3. THE GASEOUS STATE-Gases are highly compressible as compared to solids and liquids. The liquefied petroleum gas (LPG) cylinder that we get in our home for cooking or the oxygen supplied to hospitals in cylinders is compressed gas. In the gaseous state, the particles move about randomly at high speed. Due to this random movement, the particles hit each other and also the walls of the container.Matter Can Change its StateWater can exist in three states of matterSolid, as ice,Liquid, as the familiar water, andGas, as water vapour.EFFECT OF CHANGE OF TEMPERATUREOn increasing the temperature of solids, the kinetic energy of the particles increases. Due to the increase in kinetic energy, the particles start vibrating with greater speed. The energy supplied by heat overcomes the forces of attraction between the particles. The particles leave their fixed positions and start moving more freely. A stage is reached when the solid melts and is converted to a liquid. The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.The melting point of ice is 273.16 K. The process of melting, that is, change of solid state into liquid state is also known as fusion.Solid ----heat----> Liquid -------------------heat--> Gas