EVERYDAY SCIENCE

Q. Steam causes a more severe bum than boiling water. Why?

A. The amount of heat possessed bv steam (100°C) is much greater than the amount of heat possessed by water at the same temperature. This is due to the fact that to convert 1 gm of water at 100°C into steam (100°Q, 540 calories of heat are required. This additional heat contained in steam is responsible for causing more severe burns.

Q. What causes an object to look black ?

A. The colour of an object depends upon the nature of light falling on it and also on the constituent colour of the incident light reflected or transmitted by it. If all the constituent colours of the incident light are absorbed by the body, it appears black.

Q. Why is rose red and grass green in daylight ?

A. A rose appears red when daylight falls on it, because it absorbs all the constituent colours of white light except red which it reflects to us. Similarly, grass
absorbs all the constituent colours of white light except green which is reflected to us. Therefore, grass appears green to us.