Class 6 Science

1. 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?
(a) (i) and (ii) (b) (iv) only (c) (iii) and (iv) (d) (i) only
2. Which of the following statements is incorrect?
(a) All living things require air to breathe.
(b) We can feel air but we cannot see it.
(c) Moving air makes it possible to fly a kite.
(d) Air is present everywhere but not in soil.
3. 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
(a) water vapour (b) only oxygen gas (c) air (d) none of these
4. Wind does not help in the movement of which of the following?
(a) Firki
(b) Weather cock
(c) Ceiling fan
(d) Sailing yacht
5. Which of the following components of air is present in the largest amount in the atmosphere?
(a) Nitrogen (b) Oxygen
(c) Water vapour (d) Carbon dioxide
6. What is not true about air?
(a) It makes the windmill rotate.
(b) It helps in the movements of aeroplanes.
(c) Birds can fly due to presence of air.
(d) It has no role in water cycle.
7. Mountaineers carry oxygen cylinders with them because
(a) there is no oxygen on high mountains.
(b) there is deficiency of oxygen on mountains at high altitude.
(c) oxygen is used for cooking.
(d) oxygen keeps them warm at low temperature.
8. The components of air which are harmful to living beings are
(a) nitrogen and carbon dioxide.
(b) dust and water vapour.
(c) dust and smoke.
(d) smoke and water vapour.