Metallic element 'X' in period 3, having valency 2, reacts with a non-metallic element 'Y' of the same period also having valency 2. The number of non-metallic atoms in the compound formed between 'X' & 'Y' is:

1. 3
2. 1
3. 4
4. 2

1

Reason —

Element X : A metal in Period 3 with valency 2 will be present in group 2, so the element will be magnesium (Mg)

Element Y : A non-metal in Period 3 with valency 2 will be present in group 16, so the element will be sulphur (S).

Magnesium (Mg) with valency of 2 will form Mg²⁺ by the loss of 2 electrons.
Sulphur (S) with valency of 2 will form S^2- by the gain of 2 electrons.

Mg²⁺ and S^2- combine to form MgS.

∴ The number of non-metallic atoms in the compound formed between 'X' & 'Y' is 1