The components of air which are harmful to living beings are

Boojho took an empty plastic bottle, turned it upside down and dipped its open mouth into a bucket filled with water. He then tilted the bottle slightly and made the following observations.

(i) Bubbles of air came out from the bottle.

(ii) Some water entered the bottle.

(iii) Nitrogen gas came out in the form of bubbles and oxygen got dissolved in water.

(iv) No bubbles formed, only water entered the bottle. Which observations is/are correct?

Which of the following components of air is present in the largest amount in the atmosphere?

Usha took a lump of dry soil in a glass and added water to it till it was completely immersed. She observed bubbles coming out. The bubbles contain

State whether the following statements are true or false. If false, correct them.

(a) Plants consume oxygen for respiration.

(b) Plants produce oxygen during the process of making their own food.

(c) Air helps in the movements of sailing yachts and glider but plays no role in the flight of birds and aeroplanes.

(d) Air does not occupy any space.