Question

Statement I: The boiling points of the following hydrides of group 16 elements increases in the order - H₂O < H₂S < H₂Se < H₂Te
Statement II: The boiling points of these hydrides increases with increase in molar mass.
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement I and Statement II are correct.
• B. Both Statement I and Statement II are incorrect.
• C. Statement I is correct but Statement II is incorrect.
• D. Statement I is incorrect but Statement II is correct.

Answer 1

The Correct Option is B

The boiling points of hydrides usually increase with increasing molar mass because larger molecules have stronger van der Waals forces. However, H₂O is an exception due to hydrogen bonding, which is much stronger than van der Waals forces. Let's analyze both statements: 

1. Statement I: It claims the boiling points increase in the order: H₂O < H₂S < H₂Se < H₂Te. This is incorrect because H₂O has a higher boiling point than the others due to hydrogen bonding.
2. Statement II: It suggests boiling points increase with molar mass. While generally true for hydrides, H₂O is an exception, having a higher boiling point than others despite its lower molar mass due to strong hydrogen bonding. So, this statement is also incorrect when considering H₂O.

Based on this analysis, both statements are incorrect. The correct answer is:

Both Statement I and Statement II are incorrect.