Question

II. State if the following statements are True or False. Correct the false statement.
1. The principal gases of the air are hydrogen and helium.
2. Oxygen is collected by the downward displacement of water.
3. A catalyst is a substance that alters the rate of a chemical reaction.
4. Oxygen is lighter than air.
5. The action of dilute sulphuric acid on marble chips produces carbon dioxide.
III. Fill in the blanks with the correct words from the brackets.
1. The credit for the discovery of oxygen goes to . (Dalton/Priestley)
2. Oxygen is than air. (lighter/heavier)
3. Oxygen is in water. (insoluble/soluble)
4. Acid rain contains _and
. (nitric acid/chlorine, sulphur dioxide/hydrogen)
5. A mixture of smoke and fog is called
-- (moisture/smog)
IV. Match the following:
Column A
Column B
1. The catalyst used in the preparation of oxygen
(a) Helmont
2. The necessary condition for rusting to occur
(b) Carbon dioxide
3. Carbon dioxide was discovered by burning material (C) Humidity
rich in carbon
4. The amount of water vapour in air
(d) Moisture and air
5. It turns moist blue litmus red
(e) Manganese dioxide
V. Find the odd one out. Give scientific reason for your answer.
1. Oxygen, hydrogen, nitrogen, carbon dioxide
2. Water, hydrogen, oxygen, carbon​

Answer 1

Answer:

1. True

2. True

3. True

Explanation:

1. It is at the top of periodic table

2. Oxygen is collected by the downward displacement of water because it is only slightly soluble in water and is less dense than water. It cannot be collected by downward displacement of air since oxygen will get mixed with other gases in air.

3. A catalyst is a substance that alters the rate of a chemical reaction but remains chemically unchanged afterwards. The catalyst increases the rate of the reaction by providing a different reaction mechanism to occur with a lower activation energy.

Answer 2

2. true or false

1 . false. nitrogen and oxygen

2. true

3. true

4. false . heavier

5. false .Hydrochloric

3. fill in the blanks

1 . priestly

2 . heavier

3 . soluble

4 . chlorine and Sulphur dioxide

5 . smog