chapter 1

Question 1

what is matter?

Answer 1

anything that has mass and occupies space is known as matter

Question 2

what did philosophers classify matter as ?

Answer 2

in olden days philosophers classified matter as panchatatva i.e. air, fire, water, sky and earth

Question 3

how many particles of matter are present in just one crystal?

Answer 3

millions if not billions

Question 4

are matter of particles are constantly in motion ?

Answer 4

yes

Question 5

what is intermixing of 2 different type of matter own their own known as?

Answer 5

diffusion

Question 6

what energy do particles of matter posses?

Answer 6

kinetic energy

Question 7

what keeps particle of matter attracted?

Answer 7

force

Question 8

what are the three features of solid

Answer 8

1. definite volume
2. distinct boundaries
3. fixed volumes

Question 9

do liquids have fixed shape?

Answer 9

no

Question 10

do liquids have fixed volume?

Answer 10

yes

Question 11

can solid, liquid and gas diffuse in liquids

Answer 11

yes

Question 12

whose rate of diffusion is high

liquid or solid

Answer 12

liquid

Question 13

which of the following are highly compressible
gases
liquid
solid

arrange in ascending odder?

Answer 13

solid
liquid
gas

Question 14

what are three states of matter?

Answer 14

solid
liquid
gas

Question 15

what happens on increasing of temperature in solids ?

Answer 15

On 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.

Question 16

what’s the temperature ice melts at k?

Answer 16

The melting point of ice is 273.15 K

Question 17

When a solid melts, its temperature remains the same, so where does the heat energy go?

Answer 17

the heat gets used up in changing the state by overcoming force of attraction between the particles

Question 18

what is latent heat?

Answer 18

when heat gets used up in changing the state by overcoming the forces of attraction between the particles.

Question 19

what is boiling point?

Answer 19

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

Question 20

what’s the boiling point of water?

Answer 20

373k
or
100 degree Celsius

Question 21

what is sublimation ?

Answer 21

A change of state directly from solid to gas without changing into liquid state is called sublimation

Question 22

what is deposition ?

Answer 22

the direct change of gas to solid without changing into liquid is called deposition.

Question 23

what can liquefy gas?

Answer 23

Applying pressure and reducing temperature can liquefy gases

Question 24

explain the conversion of carbon dioxide?

Answer 24

Solid CO₂ gets converted directly to gaseous state on decrease of pressure to atmosphere without coming into liquid state. This is the reason that solid carbon dioxide is also known as dry ice.

Question 25

what can determine the state of a matter?

Answer 25

pressure and temperature determine the state of a substance, whether it will be solid, liquid or gas.

Question 26

define evaporation?

Answer 26

the process liquid turning into solid below its boiling point is known as evaporation

Question 27

the rate of evaporation is based on: | explain with an example

Answer 27

We know that evaporation is a surface phenomenon. If the surface area is Increased, the rate of evaporation increases. For example, while putting clothes for drying up we spread them out. an increase of temperature: .With the increase of temperature, more number of particles get enough kinetic energy to go into the vapour state. a decrease in humidity: Humidity is the amount of water vapour present in air. The air around us cannot hold more than a definite amount of water vapour at a given temperature. If the amount of water in air is already high, the rate of evaporation decreases. an increase in wind speed: It is a common observation that clothes dry faster on a windy day. With the increase in wind speed, the particles of water vapour move away with the wind. decreasing the amount of water vapour in the surrounding.

Question 28

define melting

Answer 28

Melting: The process in which solid changes into liquid is called melting. It is also called fusion.

Question 29

define freezing

Answer 29

Freezing: The process of converting liquid into solid is called freezing. e.g. convert water into ice in fridge in ice

Question 30

define boiling

Answer 30

Boiling: The process of converting liquid into vapour completely is called boiling. It is bulk phenomenon, i.e. particles from inside the liquid gain enough energy to change into vapour state. It takes place only at boiling point.

Question 31

define condensation

Answer 31

Condensation The process of converting gas or vapour into liquid is called condensation, e.g. water vapours get condensed on the surface of glass containing chilled water.

Question 32

what are the factors affecting diffusion

Answer 32

1. Density: The rate of diffusion depends upon density of liquid. Higher the density, lesser will be the rate of diffusion. 2. Temperature: The rate of diffusion depends upon temperature, i.e. the rate of diffusion increases with an increase in temperature which can be shown experimentally. 3. Physical State: Solids can diffuse into liquids slowly whereas liquids can diffuse into liquids faster and gases can also diffuse into liquids.

Question 33

The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go closer.

Answer 33

The smell of vapours coming out from hot sizzling food mix with air and reach us faster even at several meters away because rate of diffusion increases with increase in temperature. The smell of cold food cannot reach us as diffusion is slow at low temperature.