Arrange the following hydrides in increasing order of thermal stability.

A. H₂O

B. H₂Se

C. H₂Po

D. H₂Te

E. H₂S

Choose the correct answer from the options given below:

Thermal stability of group-16 hydrides decreases from H₂O to H₂Po due to decrease in bond dissociation energy.

The thermal stability of hydrides decreases as we move down within a group in the periodic table. This is primarily due to the increasing size of the central atom, which weakens the bond strength between the atom and hydrogen as you move from top to bottom in a group. For group 16 (the chalcogens), water (H₂O) is an anomaly due to its unique hydrogen-bonding capabilities, making it significantly more thermally stable than other hydrides in the same group. Thus, for the given hydrides, the order from least to most thermally stable, considering periodic trends and anomalous behavior of water, would be:

So, correct order of thermal stability is H₂O > H₂S > H₂Se > H₂Te > H₂Po