2H stands for :

1. One atom of hydrogen gas
2. One molecule of hydrogen gas
3. Two molecules of hydrogen gas
4. Two atoms of hydrogen gas

If pressure is doubled for a fixed mass of a gas, its volume will become :

1. 4 times
2. 1⁄2 times
3. 2 times
4. No change

When hydrochloric acid is added to silver chloride solution:

1. No reaction takes place.
2. A white precipitate is formed.
3. A white solution is obtained.
4. A reddish brown precipitate is formed.

Elements X, Y and Z have atomic numbers 6, 9 and 12 respectively. Which of them will form a cation :

1. Z
2. Y
3. X
4. Depends on the reactivity of the elements.