Question

The atomic number of an element X is 8 and that of element Y is 4. Both these elements can exhibit a valency of :

(a) 1

(b) 2

(c) 3

(d) 4

Answer 1

(b) 2

Atomic number of element X is 8.
Electronic configuration is 2, 6. It will gain 2 electrons to complete its octet; so, its valency is 2.
Atomic number of Y is 4.
Electronic configuration is 2, 2. It will lose 2 electrons in order to completely fill its outermost orbit . So, the valency of Y is also 2.