Acid strength of hydrides (Group 16):
Down the group, bond length increases (H–X bond gets weaker), making it easier to release H⁺. Therefore acid strength increases down the group:

\(\text{H}_2\text{O} < \text{H}_2\text{S} < \text{H}_2\text{Se} < \text{H}_2\text{Te}\)

Note: This trend is opposite to electronegativity trend, and is governed by bond dissociation energy.