Cooling from Evaporation

Q.

What kind of clothes shouldn't be worn in kitchen and laboratories

Q. It is a hot summer day, Priyanshi and Ali are wearing cotton and nylon clothes respectively. Who do you think would be more comfortable and why?

Q. Why is it said that we should not wear synthetic fibres while working near fire? List three fabrics which are safe to be worn while working near fire. [3 MARKS]

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

Q. When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.​

Q. The bristles of toothbrush are made up of fibres.

1. nylon
2. dacron
3. rayon

Q. Which are the three fabrics that are safe to be worn while working near fire

1. Cotton
2. Linen
3. Jute
4. Nylon

Q.

Water changes to ____________ on heating.

Q.

Why should we wear cotton clothes during summer?

Q. Which one of the following sets of phenomena would increase on raising the temperature?

1. Evaporation, solubility, diffusion, compression of gases
2. Evaporation, compression of gases, solubility
3. Evaporation, diffusion, expansion of gases
4. Diffusion, evaporation, compression of gases

Q. Select the statement that holds true for a chemical change.

1. Formation of new products.
2. No energy released.
3. Only a change of colour is observed in the products formed.
4. The original substance can be obtained back.

Q.

Why should we wear cotton clothes in summer?

1. Cotton provides better air circulation and a good absorber.

2. There are more patterns availible.

3. Cotton provides better air circulation.

4. Cotton is a good absorber.

Q. The following image shows the image of a lid which is used to close a vessel containing hot cooked rice. Identify the property which is undergoing a change and its cause.

1. Change in state, condensation
2. Change in colour, solidification
3. Change in smell, condensation
4. Change in taste, solidification

Q. In which of the following processes do the change in the states of matter involve the absorption of energy?
A. Boiling
B. Sublimation
C. Condensation
D. Melting

1. A and B only
2. A, B and C only
3. A, B and D
4. A only

Q. Which of the following sweaters will be the softest?

1. 100% under-hair
2. 100% beard hair
3. 75% under-hair
   25% beard hair
4. 75% beard hair
   25% under-hair

Q. What is sublimation energy??

Q. Which of the following changes are irreversible in nature?

1. Melting of candle wax
2. Woolen yarn to knitted sweater
3. Setting of cement
4. Dissolution of sugar in water

Q.

Why should we wear cotton clothes in summer?

1. Cotton provides better air circulation.

2. Cotton is a good absorber.

3. Cotton provides better air circulation and a good absorber.

4. There are more patterns availible.

Q. Assertion: Burning of paper is a permanent change.
Reason: The products formed on burning of paper cannot be converted back to paper.

1. Both assertion and reason are true. Reason is the correct explanation of assertion.
2. Both assertion and reason are true. Reason is not the correct explanation of assertion.
3. Assertion is true but reason is false.
4. Assertion is false but reason is true.

Q.

There is nothing wrong in wearing woolen dresses . Do you agree with this statement ? (2m)

Q. When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.

Q. The following image shows the image of a lid which is used to close a vessel containing hot cooked rice. Identify the property which is undergoing a change and its cause.

1. Change in state, condensation
2. Change in smell, condensation
3. Change in taste, solidification
4. Change in colour, solidification

Q. We should wear clothes during summer as they allow the sweat to easily.

1. cotton
2. condense
3. nylon
4. evaporate

Q. Identify the properties of nylon that make it a suitable choice for making parachutes.

1. fire-resistant
2. light-weight
3. excellent strength
4. water-resistant

Q. Clothes made of _________ fibres are preferred in summer.

1. cotton
2. jute
3. silk
4. woollen

Q. Clothes made of _________ fibres are preferred in summer.

1. woollen
2. jute
3. cotton
4. silk

Q. Assertion: Burning of paper is a permanent change.
Reason: The products formed on burning of paper cannot be converted back to paper.

1. Both assertion and reason are true. Reason is not the correct explanation of assertion.
2. Assertion is true but reason is false.
3. Assertion is false but reason is true.
4. Both assertion and reason are true. Reason is the correct explanation of assertion.

Q.

In which of the following processes do the change in the states of matter involve the absorption of energy?
A. Boiling
B. Sublimation
C. Condensation
D. Melting

1. A, B and D

2. A and B only

3. A only

4. A, B and C only