Identify the correct order of bond angles in the following molecules: ${\text{H}}_2\text{O}$, ${\text{H}}_2\text{S}$, ${\text{H}}_2\text{Se}$, ${\text{H}}_2\text{Te}$.

Solution

1. The bond angle in hydrides of group $16$ elements depends on the electronegativity of the central atom.
2. As electronegativity decreases from $\text{O}$ to $\text{Te}$, the bonding electrons move further from the central atom.
3. This leads to a decrease in bond-pair bond-pair repulsion.
4. Consequently, the bond angle decreases as the central atom size increases.
5. Hence the answer is (A).