Short Questions

Question 1

What do you mean by matter?

Answer 1

Anything that occupies spaces and has a mass is known as matter

Question 2

What is the SI unit of mass?

Answer 2

The SI unit of mass is kilogram (kg)

Question 3

What is the SI unit of volume?

Answer 3

The SI unit of volume is cubic metre (m³)

Question 4

What are the five basic elements of the matter?

Answer 4

The five basic elements of the matter are: air, earth, fire, sky and water.

Question 5

What happen when salt dissolve in water?

Answer 5

When we dissolve salt in water the particles of salt get into the spaces between particles of water

Question 6

What is melting point?

Answer 6

The temperature at which a solid, given sufficient heat, becomes a liquid.

Question 7

What is fusion?

Answer 7

Change of solid state into liquid state is known as fusion.

Question 8

What is the melting point temperature of an ice?

Answer 8

The melting point of ice is 273.15 K.

Question 9

What do you mean by the latent heat of the fusion?

Answer 9

The amount of heat energy that is required to change 1 kg of a solid into a liquid at atmospheric pressure at its melting point is known as latent heat of
fusion.

Question 10

What is boiling point?

Answer 10

The temperature at which a liquid starts boiling at the atmospheric pressure is called boiling point.

Question 11

Why do people sprinkle water on the roof after a hot sunny day?

Answer 11

After a hot sunny day, people sprinkle water on the roof or open ground because the large latent heat of vaporisation of water helps to cool the
surface. Water takes away the heat from the ground and gives cooling effect.

Question 12

Convert the following Celsius temperature to Kelvin temperature. -73 ° C

Answer 12

K=° C + 273 = -73 + 273 = 200 K

Question 13

Ravi was sipping hot tea from a saucer than a cup as he was in a hurry. Why do you think he was doing that?

Answer 13

Because a saucer provides more surface area than a cup for evaporation of the liquid.Hence cooling takes faster.

Question 14

‘osmosis’ is a special kind of diffusion. Comment

Answer 14

Yes, it is true because in both the phenomena, there is movement of particles from a region of higher concentration to a region of lower concentration,
however in osmosis movement takes place through semi permeable membrane which only allows solvent to pass through it.

Question 15

) On suffering from fever which will lower down your body temperature, more ice or ice cold water?

Answer 15

Ice will lower down body temperature more because it will take latent heat of fusion from our body and fever will come down faster

Question 16

What will happen to the rate of evaporation of a liquid when wind speed increases?

Answer 16

Rate of evaporation increases if wind speed increases.

Question 17

List any two properties of gas.

Answer 17

a. They have no fixed shape and volume.
b. They have intermolecular space.

Question 18

Why trees acquire more leaves during summer?

Answer 18

During summer rate of transpiration increases due to heat to keep the plant cool. More transpiration requires more leaves, hence trees acquire more
leaves in summer.

Question 19

What happens when an inflated air balloon is pricked with a pin? Name the property of the gaseous state exhibited by this observation.

Answer 19

The balloon bursts and diffusion take place.

Question 20

Define boiling point.

Answer 20

The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point.

Question 21

Define density and state its SI unit

Answer 21

Density is defined as the mass per unit volume. Its SI unit is kgm-3

Question 22

What happens when dry ice is stored in a closed container?

Answer 22

: Dry ice sublimes at room temperature. When kept in a closed container, high pressure is developed inside the container. As a result, the container
may burst.

Question 23

Why do gases exert more pressure on the walls of the container than the solids?

Answer 23

The particles in gases move randomly at high speed and they collide with each other and with the walls of the container.

Question 24

Define latent heat.

Answer 24

Latent heat is the heat energy which has to be supplied to change the state of a substance. Latent heat does not increase the temperature of a
substance. But latent heat has to be supplied in order to change the state of a substance. Latent heat can be of fusion or of vaporization.

Question 25

To which physical state of matter do the following statements apply?
i. Incompressible, no fixed shape
ii. Compressible, no definite volume

Answer 25

i. Liquid
ii. Gas

Question 26

Why sodium chloride crystal has a definite shape?

Answer 26

Strong force of attraction between the particles makes the particles remain fixed at position so it helps it to have a fixed shape.

Question 27

Define boiling point

Answer 27

The temperature at which the conversion of liquid state to vapour state takes place from the entire liquid at normal atmospheric pressure is called
boiling point.

Question 28

Sanvi dissolved 40 g of sugar in 80mL of water. She found that there is no increase in volume. Which characteristic of matter is illustrated by
this observation?

Answer 28

This observation indicates that particles of water have spaces between them into which sugar particles fit.

Question 29

Why wet clothes dry quickly in the sun than in the shade?

Answer 29

The temperature in the sunny area is higher than in the shade and evaporation takes place at a faster rate at high temperature. Hence, wet clothes
dry quickly in the sun.

Question 30

List two important properties of liquids.

Answer 30

Liquids have no definite shape. Liquids have less force of attraction between the particles.