Question

2. Why a small gap is left between the iron rails of railway tracks?

3. Take some (moderately) hot water in a tumbler. Dip one end of a steel spoon, a

plastic spoon, a glass rod ,

a wooden stick, aluminium rod and a copper rod in the hot water. After waiting for

few minutes (say 4- 5 min.)(carefully) touch the other end of each item. Observe

which ones become hot and which ones do not. Hence, categorise them as ‘heat

conductors’ or as ‘insulators’ .

4. Draw a neat, well-labelled diagram of the human respiratory system.

5. Define term heat.

6. Which device is used to measure the temperature?

7. Define respiration. Name the two types of respiration.

8. Why do we need to breathe out carbon dioxide?

9. Observe the changes in a leaf when both of its surfaces are coated with Vaseline?

Give a simple explanation of your observations.

10. Record the breathing rate, of your family members (i)when at rest and after (ii) after

performing the activities. Enter your result in table given below:​

Answer 1

Answer:

1 :The gaps left between successive rails on a railway track, the reason is that the rails expand in summer. The gap is provided to allow for this expansion.