The composition of the nucleus of deuterium is:

1. 1e^– and 1P
2. 1P and 1n
3. 1n and 1e
4. 2P and 1e^–

Thin strips of magnesium, copper and iron are taken.

(a) Write down what happens when these metals are treated as follows

(i) Heated in presence of air

(ii) Heated with dil. HCl

(iii) Added to an aqueous solution of zinc sulphate

(b) Arrange these metals in descending order of reactivity.

Hydrogen is evolved by the action of cold dil. HNO₃ on

1. Fe
2. Cu
3. Mg
4. Zn

Elements which show unique nature in the preparation of hydrogen are

1. Na, K, Li
2. Mg, Ca, Ba
3. Al, Zn, Pb
4. Fe, Cu, Ag