Q:- What will be the weight of a person on moon? Will it be less or more than his weight on the earth?

Ans:- As the acceleration of the gravity of the moon is one-sixth that of the earth; therefore the weight of a person on the surface of the moon will be one-sixth of his actual weight on earth.

Q :- Why do some liquids burn while others like water do not?

Ans:- A liquid burns if its molecules can combine with oxygen in the air with the production of heat. Therefore, the liquids like oil burns but water does not.

Q :- Why does iron sink in water but float in mercury?

Ans:- It is simple. As the density of iron is more than that of water but less than that of mercury thus it sinks in water and float in mercury.

Q. Why does fog occur?

Ans: Fog occurs due to the factors like humidity and condensation. The fog occurs when air reaches at a point of very high humidity. Very high humidity means that air does not absorb more humidity. When the air rapidly cools, then condensation (it is process in which gas changes to liquid) occurs that leads to fog.

Do you know that the foggiest place of the earth is the “Grand banks” at the island of the “Newfoundland”.

Q:- Why the wood make cracking sound after burning?

Ans:- As the wood contains a complex mixture of gases and tar-forming vapors trapped under its surface therefore when the wood burns these gases and tar vapors escape, making a cracking sound.