What do you observe when

(a) Ice cold water is filled in a glass tumbler.

(b) A burning candle is covered with an inverted jar.

(c) Carbon dioxide gas is passed through lime water.

(d) A beam of light is allowed to enter in a closed dark room through a small hole.

(a) When ice cold water is filled in a glass tumbler, we will observe that fine water droplets get deposited on the outer wall of the glass tumbler. This is due to the cold surface of the glass tumbler, the water vapour present in air get condensed as water droplets. This proves that air contains water vapour.

(b) When we cover the burning candle with an inverted jar, we will notice that after a few minutes, the flame gets extinguished. This is because the oxygen in the air trapped in the inverted jar is used up and the candle does not get any more oxygen for burning.

(c) Carbon dioxide reacts with lime water to form white insoluble calcium carbonate which gives milky white appearance to the solution. This confirms the presence of carbon dioxide in air.

(d) A beam of light is allowed to enter in a closed dark room through a small hole. We will observe randomly moving dust particles in the beam of light. This confirms the presence of dust particles in the air.