Evaporation

Q.

Name the technique used to separate camphor from salt.

Q.

Examples of evaporation cause cooling.

Q.

Which separation techniques will you apply for the separation of the following?

(1) Sodium chloride from its solution in water.

(2) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride.

(3) Small pieces of metal in the engine oil of a car.

(4) Different pigments from an extract of flower petals.

(5) Butter from curd.

(6) Oil from water.

(7) Tea leaves from tea.

(8) Iron pins from sand.

(9) Wheat grains from husk.

(10) Fine mud particles suspended in water.

Q.

How will you demonstrate that water vapour is present in air?

Q. How boiling is a bulk phenomenon whereas evaporation is a surface phenomenon?

Q.

What happens when a liquid becomes a gas?

Q.

What do you mean by bulk phenomenon?

Why boiling is called bulk phenomenon?

Q.

Describe a method to separate a mixture of common salt and sand.

Q. On a hot sunny day people Sprinkle water on the roof or open ground why

Q.

Below the boiling point of a liquid evaporation takes place. Then when the liquid is being heated to vaporise it, before reaching its boiling point does the liquid not evaporate?

Q. What will be the boiling point at hill station?

Q. What is the difference between vaporization and evaporation

Q.

Why does all the water of the earth not get evaporated during hot summer days ?

Q.

Why does our palm feel cold when we put some acetone (or perfume) on it?

Q.

What happens when you pour some acetone on your palm?

1. The particles lose energy and evaporate causing the palm to feel cool.

2. The particles gain energy from the palms or surroundings and evapoarte causing palm to feel cool.

3. The particles lose energy from the palms and condensate causing the palm to feel hot.

4. All the options are correct.

Q.

We find water droplets on the surface of leaves, especially in the early morning. This is because of:

1. early morning showers

2. watering of plants the previous night

3. condensation of water vapour in the air

4. evaporation of water from leaf surface

Q.

Boiling point of a liquid on hill station like shimla is lower than that in delhi . Why

Q.

Which condition out of the following will increase the evaporation of water?

1. Increase in temperature of the water

2. Decrease in temperature of the water

3. The less exposed surface area of water

4. Adding common salt to the water

Q.

Why do we feel cool under a fan when we perspire?

Q. On a hot sunny day why do we feel pleasant sitting under a tree?

Q.

Sarita wanted to separate dye from blue ink. Her teacher told her that heating the ink over a water bath will give her the results. What is the name of the process that her teacher suggested?

1. Filtration

2. Evaporation

3. Sedimentation

4. Decantation

Q.

Enumerate the changes that take place inside the matter during the change of states.

Q. 1. Write the temperature required for the differentstates of water in kelvin(i) Liquid(ii) Gaseousii) Solid

Q.

Evaporation of a liquid takes place at temperature:

1. below the freezing point

2. below the boiling point

3. above the freezing point

4. above the boiling point

Q.

Which of the following is not a pure substance?

1. Tap water

2. Nitric acid

3. Mercury

4. Distilled water

Q.

Why does our palm feel cold when we put some acetone, petrol or perfume on it?

Q.

How will you separate a mixture containing sand and sugar ?

Q.

Which is the best technique to separate coffee grains from coffee solution?

1. Evaporation

2. Distillation

3. Filtration

4. Chromatography

Q. Suggest separation technique(s) one would need to employ to separate the following mixtures.

(a) Mercury and water

(b) Potassium chloride and ammonium chloride

(c) Common salt, water, and sand

(d) Kerosene oil, water, and salt

Q.

When the vapour pressure of a liquid is equal to its atmospheric pressure, then it

1. Boils

2. Freezes

3. cools down

4. Does not undergo any change