Question

Elements $X,Y$ and $Z$ have $4,5$ and $7$ valence electrons respectively. Write the molecular formula of compounds formed by these elements individually with hydrogen.

Answer 1

Valency of $X=8-4=4$

Valency of $Y=8-5=3$

Valency of $Z=8-7=1$

So molecular formulae of these compounds with hydrogen are

$\left(a\right)X{H}_4$

$\left(b\right)Y{H}_3$

$\left(c\right)HZ$