Hot and cold

Q.

Warm air is ______ than cold air.

1. denser
2. heavier
3. either heavier or lighter
4. lighter

Q.

Select the correct statement among the following?

1. Hot air is heavier than cold air

2. Hot air is lighter than cold air

3. Depends on atmospheric condition

4. Both are equally heavy

Q.

Warm air is less denser than cold air.

1. True

2. False

Q.

The transfer of heat that occurs in liquids and gases is called _______.

Q.

The hot air rises up the atmosphere.

Say True or False.

1. False

2. True

Q.

Handles of frying pans are made of ____________conductor of heat.

Q.

Why handle of pan made of plastic?

Q.

Convection needs a medium.

1. True
2. False

Q.

_____________ are responsible for causing wind and monsoon rain.

Q.

Convection cannot take place in solids because___________

1. actual movement of particles is not possible

2. solids possess free electrons

3. atoms are loosely packed

4. they are bad conductors

Q.

What is convection in thermal energy?

Q.

Hot air being less dense rises up.

1. True
2. False

Q.

Water and bakelite are ________ conductors of heat.

Q.

Suppose a body A at a higher temperature is brought into contact with another body B at a lower temperature. Which of the following is/are true?

1. Atoms of Body A become less active

2. Atoms of Body B become more active

3. Atoms of Body A become more active

4. Atoms of Body B become less active

Q.

Convection is not possible in

1. Water

2. Air

3. Vacuum

4. All of these

Q.

Which of the following is not used to make handles of cooking vessels?

1. plastic

2. aluminum

3. wood

Q.

Select the correct statement(s) among the following?

1. Hot air is heavier than cold air

2. Hot air is lighter than cold air

3. Both are equally heavy

4. Depends on atmospheric condition

Q. In a thermos flask, explain how are the heat losses minimised from its contents by (i) conduction, (ii) convection and (iii) radiation?

1. Ans required.

Q.

Define the following.

Convection.

Q.

Himanshu has three buckets as shown below. He puts his left-hand in bucket A and right-hand in bucket B. He then puts both of his hands in normal water. His left-hand feels that the water here is hotter while his right-hand feels that the water here is colder.

Select the correct option:

1. A is hotter than B

2. B is hotter than A

3. A and B are equally hot

4. Can’t be said

Q.

Himanshu has three buckets as shown below. He puts his right-hand in bucket A and left-hand in bucket B. He then puts both of his hands in normal water. His right-hand feels that the water here is hotter while his left-hand feels that the water here is colder.

Select the correct option:

1. A and B are equally hot

2. Can’t be said

3. B is hotter than A

4. A is hotter than B

Q.

Find the odd one among the given:

width, height, thickness, hotness

Q. Himanshu has three buckets as shown below.

He puts his left hand in bucket A, and his right hand in bucket B. He then puts both of his hands in normal water. His left hand experiences that the water is hotter while his right hand feels that the water is colder. Select the correct option.

1. Water in bucket A is hotter than water in bucket B.
2. Water in bucket B is hotter than water in bucket A.
3. Water in bucket A and B are equally hot.
4. The relative hotness of the buckets A and B cannot be determined.

Q. Thermos flask prevents loss or gain of heat by

1. conduction only
2. convections only
3. radiation only
4. all of the above

Q.

Himanshu has three buckets as shown below. He kept his right-hand in bucket A and left-hand in bucket B. Then, he kept both of his hands in normal water. His right-hand feels that the water is hotter while his left-hand feels that the water is colder.

Select the correct option:

1. Can’t be said

2. A is hotter than B

3. B is hotter than A

4. A and B are equally hot

Q. What allows air to move side ways? Which air moves(hot or cold)?

Q.

2. Why are handles of utensils made up of wood or plastics?

Q. Given below are four objects:
(i) The base of a frying pan taken from the flame
(ii) Ice cream
(iii) Snow
(iv) Molten wax

Which of the following object(s) given above is/are hot?

1. i and iv
2. i only
3. iii and iv
4. i, ii and iii

Q. Himanshu has three buckets as shown below. He puts his right hand in bucket A and left hand in bucket B. He then puts both of his hands in normal water. He feels hotness in his right hand and coldness in his left hand.
What can be said about the hotness of water in buckets A and B?

1. The water in bucket A is hotter than in bucket B.
2. The water in bucket B is hotter than in bucket A.
3. The water in buckets A and B is equally hot.
4. Cannot be predicted

Q.

when we are in a bus , the bus is filled with air. Then when it moves the air rushes in through the window. why does this happen when the bus is already filled with air?