Evaporation

Q.

A patient suffering from high fever is advised to put wet cloth strips on his forehead. Why?

Q. What is sublimation? Give a few examples of substances that undergo sublimation.

Q.

What is evaporation?

Q. Which of the following conditions is most favourable for converting a gas into a liquid?

1. High pressure, low temperature
2. Low pressure, low temperature
3. Low pressure, high temperature
4. High pressure, high temperature

Q.

What happens when gas is cooled?

Q.

If water is filled in an ice cube tray and put into the freezer then water converts to solid ice cubes after some time. This phase transition process occurs due to ___ and it is called ____ .

1. Solidification

2. Melting

3. Sublimation

4. Evaporation

Q.

During the evaporation of liquid:

1. The temperature of the liquid will rise.

2. The temperature of the liquid will fall.

3. May rise or fall depending on the nature.

4. May rise or fall depending on the nature.

Q. Thoughts are considered as matter.

1. False
2. True

Q.

Explain with an example to demonstrate that when a liquid evaporates, it takes heat from its surroundings.

Q.

What are the ways of representing a chemical reaction?

Q. Which phenomenon occurs during drying of wet clothes?

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

Q.

Does evaporation of a liquid takes place at a fixed temperature?

Q.

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

1. Evaporation takes place only at ${100}^{\circ }\text{C}$.
2. Evaporation takes place at a temperature below ${100}^{\circ }\text{C}$.
3. Evaporation takes place only above ${100}^{\circ }\text{C}$.
4. Both evaporation and boiling are same.

Q.

A gas completely fills the vessel in which it is kept. Why?

Q.

Which among the following is a surface phenomenon?

1. Boiling

2. Melting

3. Evaporation

4. Freezing

Q.

Why is cooling produced on evaporation of a liquid?

Q.

The process by which wet clothes dry up is called as:

1. Sublimation

2. Boiling

3. Evaporation

4. Condensation

Q. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Why are cotton clothes more suitable to wear than synthetic clothes during the summer season?

Q.

Why do we use Erlenmeyer flask instead of normal glass beakers in critical lab tests?

1. Erlenmeyer flasks are easily available

2. None of the choices

3. Erlenmeyer flasks with narrow neck helps prevent accidental splashes

4. Erlenmeyer flasks with narrow neck help reduce evaporation of liquids

Q. An increase in temperature decreases the rate of evaporation.

1. True
2. False

Q.

____________ is a process that separates a pure solid in the form of its crystals from a solution.

1. Filtration
2. Crystallisation
3. Condensation
4. Sedimentation

Q.

We heat ink to obtain the coloured component (dye) in a watch glass (similar to a glass cup). The process involved here is ______ and the component removed from ink is ________.

1. Evaporation, water

2. Sublimation, water vapour

3. Melting, water vapour

4. Condensation, oil

Q. Evaporation occurs only at the surface of the liquid.

1. False
2. True

Q.

What is evaporation?

Q. Ink is heated to obtain the coloured component (dye) in a watch glass. The process involved here isand the component removed from ink is.

1. oil
2. water
3. condensation
4. evaporation

Q.

Name the process of vaporisation that takes place only from the surface of liquid .

Q.

Collisions between molecules in gases are _________ in nature.

Q.

Drying of wet clothes in an open terrace takes place due to the phenomenon of___ .

Q.

We obtain dissolved solid from its solution by the process of:

1. Filtration

2. Evaporation

3. Centrifugation

4. Melting

Q. Before the doctor gives an injection, he applies spirit at that spot. At that time our skin feels very cool because:

1. the spirit evaporates using the heat from our body.
2. the spirit kills the bacteria present on the skin.
3. the spirit is at low temperature.
4. the spirit loses its heat when it is taken out of the bottle.