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

option (b)

Element X

Atomic number = 8
Electronic configuration = 2, 6 [2 electrons in K orbit, 5 electrons in L orbit]
Valency = -2

Element Y

Atomic number = 4

Electronic configuration = 2, 2 [2 electrons in K orbit, 2 electrons in L orbit]
Valency = +2