matter in our surroundings

Question 1

What is matter?

Answer 1

Anything which occupies space and mass is called matter.

Question 2

What are the characteristics of the particles of the matter?

Answer 2

1. Particles of matter have space b/w them.
2. Particles of matter are continuously moving.
3. Particles of matter attract each other.
4. Particles of matter are very small.

Question 3

What is diffusion?

Answer 3

The intermixing of particles of two different types of matter on their own is called matter.

Question 4

What is K.E?

Answer 4

Energy possesed due to the motion of particles is called is K.E.

Question 5

Write properties of solid state?

Answer 5

Solid has a definite volume, definite shape, have negligible compressibility and is rigid.

Question 6

Sponge is a solid and still we are able to compress it. why?

Answer 6

It is because sponge has minute holes, in which air is trapped. When we press it, the air is expelled out from its holes making it highly compressible.

Question 7

Rubber band changes is shape on stretching. Why is it salt?

Answer 7

This is because a rubber changes it’s shape under force and regains the same shape when the force is removed.

Question 8

Write the properties of liquid state.

Answer 8

A liquid has a definite volume, no definite shape and cannot be compressed much.

Question 9

How does aquatic animal breath under water?

Answer 9

The gas is from the atmosphere, especially oxygen and carbon dioxide diffuse and dissolve in water. The aquatic animals and plants can breathe underwater due to the presence of dissolved oxygen in water.

Question 10

Write the properties of gaseous state.

Answer 10

A gas doesn’t have definitely volume and fixed shape. It has high compensibility

Question 11

In the gaseous state how does its particles exert pressure?

Answer 11

In the gaseous state, the particles move about randomly at high-speed. Due to this movement, they hit each other and also the walls of the container. It causes gas to exert pressure.

Question 12

What is the meeting point ?

Answer 12

The temprature at whicha solid melts to become a liquid at atmospheric pressure, is called its meeting point.

Question 13

What is boiling point?

Answer 13

The temprature at which liquid starts boiling at the atmosphere pressure is known its boiling point.

Question 14

Why temperature do not change during change

Answer 14

The temperature of substances remains constant at melting and bolling point until all the substances melt above because the heat supplied is continuously used in changing the state of substance by overcoming the force of attraction between the particles.

Question 15

What is latent heat of fusion?

Answer 15

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

Question 16

What is latent heat of vaporization?

Answer 16

The amount of heat energy that is required to change I kg of liquid into vapour state at atmospheric pressure at its boiling point is known as latent heat of vapourisation.

Question 17

Why ice at 273 k is more effective in cooling thenwater at same temperature.

Answer 17

Ice at 273 k will teach latent heat from the medium to convert itself into water at 273k then into water but in case of water at 273 k, there will be no change in state and, it cannot take lantent heat from the medium. Hence ice will absorb more heat and causes more cooling.

Question 18

Why steam causes more severe burn than boiling water at 100 C .

Answer 18

Steam contain more heat in the form of latent heat of vaporisation than boiling water. So when steam falls on the skin, it gives out extra heat as compared to water at same temperature and causes more severe burns.

Question 19

What is sublimation?

Answer 19

The changing of state directly from solid to gas without changing into liquid sate is called sublimation.

Question 20

What is dry ice?

Answer 20

Solid CO₂ gets covered directly into gaseous state on decreasing the pressure to 1 atmosphere without coming to liquid state. So solid CO₂ is stored under pressure and is called dry ice.

Question 21

Define evaporation.

Answer 21

The process of changing liquid into vapor even below its boiling point is called evaporation.

Question 22

Write the factors that affects evaporation.

Answer 22

1. Surface area: If the surface area is increased, rate of evaporation increases.
2. Temperature: With the increase of temperature, more no. of particles get enough K.E to go into vapour state. So rate of evaporation increases with increase of temperature.
3. Humidity: Decrease in humidity increase the rate of evaporation. Humidity is the amount of water vapour present in the air.
4. Wind speed: Increase in wind speed, increase the rate of evaporation.

Question 24

How does evaporation causes cooling?

Answer 24

In evaporation only high energy particles leave the liquid surface. The particles of liquid absorb energy from the surrounding to regain the energy lost during evaporation. This absorption of energy from the surroundings makes the surrounding cool.

Question 25

Then we put acetone on our palm why does are palm feel cool?

Answer 25

when acetone is put on our
palm, its particles gain energy from palm or surroundings and evaporate causing the palm to feel cool.

Question 26

Why do we wear cotton clothes in summer?

Answer 26

During summer we perspire more. The sweat takes the heat from our body and evaporates away. This makes us cool. Cotton Being a good absorber of water absorbs these sweat and exposes it to air for easy evaporation. So we prefer cotton clothes in summer.

Question 27

In earthern pot the water get cool . Why

Answer 27

The fine pores is Arden. Port allows the water particles to come out an outer surface Off the pot. This water evaporates continuously and takes the latent required for vapourisation from the water in the pot. In this process water gets cooled.

Question 28

Why people sprinkle water on ground on hot summer days?

Answer 28

People sprinkle water on ground on hot summer days. This water gets evaporates by taking large latent heat of vaporistaion from the ground, leaving behind the surface cool.

Question 29

How does dessert cooler causes cooling?

Answer 29

When hot and dry air passes through big pads of grass water takes heat from air and evaporate. This evaporation causes cooling of air.

Question 30

A desert cooler cool paper on a hot and dry day. Why?

Answer 30

Higher temprature and dryness of air increases the rate of evaporation. And due to increased rate of evaporation a desert cooler gives better cooling on a hot and dry day.

Question 31

Why are we able to sip hot tea faster from a saucer than a cup?

Answer 31

Saucer has a larger surface area than cup. So rate of evaporation is more in saucer. Hence more cooling will be done in the case of saucer. Hence we are able to sip hot tea faster from a saucer than a cup.