Evaporation

Q.

What is evaporation? Explain it on the basis of the molecular motion.

Q.

Patient suffering patient suffering from high fever is advised to put wet cloth stripes on his forehead. Why

Q.

With the help of an activity show that the rate of evaporation increases with increase in surface area.

Q.

Why does the rate of evaporation increase with increase in temperature?

Q.

The process of conversion of liquid to vapour is called________

1. Condensation

2. Boiling

3. Sublimation

4. Evaporation

Q.

Define:

Condensation point.

Q.

Give reasons for the following observation :

The smell of hot sizzling food reaches you several meters away, but to get the smell from cold food you have to go close ?

Q.

Do all the molecules of a liquid take part in evaporation? If not, explain your answer.

Q.

The rate of evaporation increases with

1. decrease in surface area

2. increase in surface area

3. decrease in temperature

4. increase in humidity

Q. Steam produces more severe burns than boiling water. Think why?

Q.

Why do we keep water in earthen pots during summer?

Q.

Which of the following option correctly differentiates between evaporation and boiling?

1. Both evaporation and boiling are same.

2. Evaporation takes place only at ${100}^{\circ }C$.

3. Evaporation takes place at any temperature that is below boiling point.

4. Evaporation takes place at any temperature above boiling point.

Q.

When the gas reaches its condensation point it becomes what?

Q.

Identify the factors that affect the process of evaporation.

1. Temperature

2. Surface area

3. Humidity in air

4. All the above options are correct.

Q.

When we put acetone (nail polish remover) in our hand, we will feel cold. Why?

1. Evaporation of petrol.

2. Boiling of petrol over your hand.

3. Melting of petrol on your hand.

4. Freezing of petrol on your hand.

Q.

6. In which of the following cases, evaporation of water will be the slowest.

1. A tray of water kept in sunlight

2. A kettle of water kept on a burner

3. A glass of water kept in a room

4. A bucket of water kept on the rooftop

Q.

The process of changing a gas (or vapour) to a liquid by cooling, is called _______________.

Q. Explain evaporation on the basis of molecular motion?

Q. Dogs hang out their tongue during summers to achieve cooling. Which phenomenon is involved in the process?

1. Fusion
2. Evaporation
3. Vaporization
4. Condensation

Q. The process of conversion of water into its vapour is called as .

1. Evaporation
2. Precipitation
3. Condensation

Q.

During sublimation a solid on heating turns. directly into ______ [liquid/vapour]

Q. 1L of water is kept in 4 different bowls having surface areas as 50 $m^2$, 100 $m^2$, 150 $m^2$, 200 $m^2$ respectively. Arrange the surface areas in the increasing order of rate of evaporation.

1. $100m^2$ < $150m^2$ < $200m^2$ < $50m^2$
2. $50m^2$ < $200m^2$ < $150m^2$ < $100m^2$
3. $50m^2$ < $150m^2$ < $200m^2$ < $100m^2$
4. $50m^2$ < $100m^2$ < $150m^2$ < $200m^2$

Q. The process due to which a gas changes into a liquid at a fixed temperature is called vaporization. True or false

1. True
2. False

Q.

Doctors advice to put strips of wet cloth on the forehead of the person having high fever. Why?

Q. Process of change of state from gaseous state to liquid state is called:

1. Freezing
2. Sublimation
3. Condensation
4. Boiling

Q.

Evaporation takes place

1. over half the liquid depth

2. over the surface of liquid

3. over the entire liquid

4. over quarter depth of liquid

Q.

It is desired to increase the rate of evaporation of a given quantity of a liquid. Suggest two ways, excluding the direct heating of the liquid, which can be used to bring about this increase in the rate of evaporation.

Q.

When I am increasing pressure the boiling point is increasing , then when I am changing gas into liquid or liquid into solid under high pressure in low temperatures, what is the factor increasing or decreasing to turn it into a liquid or gas?

Q.

A liquid can change into vapour state-

1. At a fixed temperature

2. At all temperature

Name the process involved in two cases.(Also give two major differences between the process mentioned above.)

Q. Water inside an earthern pot as the water molecules evaporate through pores, heat from/to the surroundings.

1. cools down
2. heats up
3. releasing
4. absorbing