VSAQ for Ch 1 Matter in Our Surroundings Class 9 Science NCERT
Important Questions1
Name the state of matter in which particles just move around randomly because of very weak force of attraction.
Answer
Gaseous state
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2
Give two examples of practical applications which is based on high compressibility of gases.
Answer
CNG, LPG
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3
A substance has a finite volume but not a definite shape. Write the physical state of substance.
Answer
Liquid
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4
Name the property of gases that helps aquatic plants and animals to survive in water.
Answer
Solubility in water
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5
Identify the name of the material which has no fixed shape but a fixed volume : Wood, a piece of iron, oxygen and water.
Answer
Water
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6
Name the property of gases due to which it is possible to fill CNG in cylinders for using as fuel in cars.
Answer
Compressibility
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7
When a drop of blue ink is put in water, the blue colour spreads and the whole solution becomes blue. Name the phenomenon due to which this happens.
Answer
Diffusion
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8
A substance has no mass; can we consider it as matter ?
Answer
No
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9
Mention two factors that need to be varied to liquefy atmospheric gases.
Answer
Temperature and Pressure
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10
Select the substances from the following which do not have the property of sublimation: Camphor, Potassium permanganate, Copper sulphate, Naphthalene.
Answer
Potassium permanganate, Copper sulphate.
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11
Arrange the following substances in the increasing order of force of attraction between their particles: Oxygen, salt, milk.
Answer
Oxygen < Milk < Salt
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12
What happens when you open a bottle of perfume?
OR
We can get the smell of perfume sitting several metres away. Give reason.
Answer
Particles of perfume diffuses into the air and can be smelled even at a distance.
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13
A crystal of Copper sulphate is dropped in a glass of water and is allowed to settle at the bottom. After some time it is observed that the blue colour appears just above the solid crystal and with the passage of time whole water in glass turns blue. Identify the characteristic of particles of matter associated with this observation.
Answer
Particles of matter are continuously moving.
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14
Why do liquids have mostly lower density than solids?
Answer
Liquids have less force of attraction between molecules i.e. less mass and more volume as compared to solids.
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15
A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Answer
Particles of water are held together by weak forces of attraction. It is these forces of attraction which the diver cuts through water in the swimming pool.
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16
A gas jar 'X' containing air is inverted over another jar 'Y' containing a brown gas which is heavier than air. After some time brown colour is also observed in the gas jar 'X'. Identify the phenomenon associated with this observation.
Answer
Diffusion
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17
Sponge is a solid, yet we are able to compress it Why?
Answer
A sponge has minute holes, in which air is trapped. When we press it, air is expelled out and we are able to compress it.
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18
When 2 ml of dettol is dissolved in 100 ml of water, the smell can be detected even on repeated dilution. Identify the physical nature of matter.
Answer
Particles of matter are very small which can be dissolved in water, diffusing its smell readily in air.
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19
If the food is being cooked in the kitchen, name the process which brings smell.
Answer
Due to high speed of particles and large space between them, gases show the property of diffusing very fast. Name of the process is diffusion.
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20
Why does palm of your hand feel cold when you pour some acetone on your palm ?
Answer
Acetone has very low boiling temperature. It will evaporate taking latent heat of vaporization from the palm. The hand looses heat and gets cooled leaving temperature on hand low.
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21
What is meant by latent of fusion ?
Answer
The amount of heat energy that is required to change 1 kg of a solid into liquid at atmospheric pressure at its melting point is known as the latent heat of fusion.
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22
State one difference between gas and vapour.
Answer
Gas: It is a stable state as compared to vapour. Example: O2, H2.
Vapour: It is an unstable state. On normal cooling, vapour changes into liquid state.
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23
Name the phenomenon of changing of a liquid into vapours at a temperature even below its boiling point.
Answer
Evaporation
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24
The boiling point of alcohol is 78°C. What is the corresponding temperature on the Kelvin scale?
Answer
78 + 273 = 351 K
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25
The boiling point and freezing point of water are 100°C and 0°C respectively. Convert these temperatures in K.
Answer
100°C + 273 = 373 K 0°C + 273 = 273 K
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26
Kinetic energy of particles of water in three vessels A, B, C are EA, EB, and EC respectively and EA > EB > EC. Arrange the temperatures TA, TB and TC of water in the three vessels in increasing order.
Answer
TC < TB < TA
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27
The molecules of water have more energy as compared to molecules of ice at same temperature. Justify this statement.
Answer
Water has more energy than ice at same temperature because particles in water have absorbed more energy during the change of state.
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