Question

Statement I Acidic character increases from $H _{2} O$ to $H _{2} Te$.
Statement II The reason is a decrease in bond enthalpy for the dissociation of $H -E$ bond down the group.

• A. Statement $I$ and Statement $II$ are correct and Statement $II$ is the correct explanation of Statement $I$.
• B. Statement $ I$ and Statement II are correct but Statement II is not the correct explanation of Statement $I$.
• C. Statement $I$ is correct but Statement $II$ is incorrect.
• D. Statement $II$ is correct but Statement $I$ is incorrect.

Answer 1

Answer: (A)

Elements of group-16 form hydrides of the type $H _{2} E$ $(E= O , S , Se$, Te and $Po )$. Their acidic character increases from $H _{2} O$ to $H _{2} Te$ due to decrease in bond enthalpy for the dissociation of $H -E$ bond down the group.
It also results in the decrease in the thermal stability of hydrides from $H _{2} O$ to $H _{2} Po$. All the hydrides except water possess reducing property and this character increases from $H _{2} S$ to $H _{2} Te$.