Given below are two statements: Statement I: The boiling point of hydrides of Group 16 elements follow the…
Given below are two statements:
Statement I: The boiling point of hydrides of Group 16 elements follow the order
$\mathrm{H}_2 \mathrm{O}\gt\mathrm{H}_2 \mathrm{Te}\gt\mathrm{H}_2 \mathrm{Se}\gt\mathrm{H}_2 \mathrm{~S} \text {. }$
Statement II: On the basis of molecular mass, $\mathrm{H}_2 \mathrm{O}$ is expected to have lower boiling point than the other members of the group but due to the presence of extensive H -bonding in $\mathrm{H}_2 \mathrm{O}$, it has higher boiling point.
In the light of the above statements, choose the correct answer from the options given below:
Both Statement I and Statement II are false
Statement I is true but Statement II is false
Statement I is false but Statement II is true
Both Statement I and Statement II are true
Solution
Statement I is correct, because boiling point of hydrides of group 16 follows the order
$\mathrm{H}_2 \mathrm{O}\gt\mathrm{H}_2 \mathrm{Te}\gt\mathrm{H}_2 \mathrm{Se}\gt\mathrm{H}_2 \mathrm{~S} \text {. }$
Statement II due to intermolecular H -bonding $\mathrm{H}_2 \mathrm{O}$ shows higher boiling point than respective hydrides of group 16.
(Both Statement are true)
Order from $\mathrm{H}_2 \mathrm{Te}$ to $\mathrm{H}_2 \mathrm{~S}$ is due to decreasing molar mass.