Element X has atomic number 8 and element Y has atomic number 15. Which of the following statements is correct regarding valency of X and Y?
1
Valency of X is 6 and that of Y is 3
2
Valency of X is 6 and that of Y is 5
3
Valency of X is 2 and that of Y is 3 or 5
4
Valency of X is 2 and that of Y is 3 only