of central atom increases which weakens the

\(\mathrm{M}-\mathrm{H}\) bond. Since, the size increases from \(\mathrm{S}\) to \(\mathrm{Te}\)

thus acidic strength follows the order.

\(H_{2} S < H_{2} S e < H_{2} T e\)

Acidic nature \(\propto \frac{1}{\text { Bond disspciation enthalpy }}\)

\(S\) to \(Te\) size increases, bond dissociation enthalpy

decreases and acidic nature increases.