During an endothermic reaction:

1. The temperature of surroundings increases.
2. The temperature of surroundings decreases
3. The heat in the surroundings increases
4. The reactants melt.

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

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.

The atomic numbers of elements A, B, C and D are 2, 6, 12 and 20 respectively. Which of them has 2 electrons in its N shell?

1. A
2. D
3. B
4. C