Concept:In group 16 hydrides, acidic strength increases down the group because the H–E bond becomes progressively weaker.
Explanation:The hydrides of group 16 elements are
H2O,
H2S,
H2Se, and
H2Te.
Moving down the group, the atomic size of the element increases.
As a result, the bond dissociation enthalpy of the H–E bond decreases from
H2O to
H2Te.
A weaker H–E bond breaks more easily, releasing
H+ ions readily.
Hence, the acidic character increases from
H2O through
H2S and
H2Se to
H2Te.
Therefore, the correct decreasing order of acidity is:
H2Te>H2Se>H2S>H2OAnswer:Option C:
H2Te>H2Se>H2S>H2O