JEE Chemistry 2025 Question with Solution

Given: Two statements about the hydrides $H_2Se$ and $H_2Te$.

Find: Which statement is true and which is false.

For group $16$ hydrides, acidity increases down the group because atomic size increases and the H-X bond becomes weaker. The acidity trend is:

Therefore, $H_2Te$ is more acidic than $H_2Se$. So, Statement I is false.

Bond enthalpy decreases down the group because larger atoms form weaker bonds. Hence the bond involving selenium is stronger than the bond involving tellurium:

Therefore, $H_2Se$ has higher bond enthalpy for dissociation than $H_2Te$. So, Statement II is true.

Therefore, Statement I is false but Statement II is true. The correct option is A.

Given: Compare acidity and bond enthalpy of $H_2Se$ and $H_2Te$.

Find: The correct option using periodic trends.

Analysis of Statement I: Acidity of hydrides increases down the chalcogen group:

Since tellurium is larger than selenium, the bond to hydrogen is weaker in $H_2Te$ and proton release is easier. Hence, the statement "$H_2Se$ is more acidic than $H_2Te$" is false.

Analysis of Statement II: Bond enthalpy decreases down the group as atomic size increases. Selenium is smaller than tellurium, so the bond in $H_2Se$ is stronger and requires more energy for dissociation than the bond in $H_2Te$. Hence, Statement II is true.

Thus, the correct option is A, that is, Statement I is false but Statement II is true.