Given below are two statements :
Statement I : The increasing order of boiling point of hydrogen halides is $$HCl < HBr < HI < HF$$.
Statement II: The increasing order of melting point of hydrogen halides is $$HCl < HBr < HF < HI$$.
In the light of the above statements, choose the correct answer from the options given below :

Statement I: Increasing order of boiling points: HCl < HBr < HI < HF.

Since boiling points are influenced by hydrogen bonding and molecular weight, we recall the values for hydrogen halides.

• HF: 19.5°C (very high due to strong hydrogen bonding)
• HCl: −85°C
• HBr: −66.8°C
• HI: −35.4°C

This gives the trend HCl (−85°C) < HBr (−66.8°C) < HI (−35.4°C) < HF (19.5°C), which confirms the proposed order ✓

Statement I is TRUE.

Statement II: Increasing order of melting points: HCl < HBr < HF < HI.

Substituting the known melting points for these compounds yields:

• HF: −83.6°C
• HCl: −114.2°C
• HBr: −86.8°C
• HI: −50.8°C

From the above, the sequence becomes HCl (−114.2°C) < HBr (−86.8°C) < HF (−83.6°C) < HI (−50.8°C) ✓

Statement II is TRUE.

Note that for melting points, HF does not maintain the highest value despite hydrogen bonding; instead, HI exhibits the highest melting point due to its larger molecular size and stronger van der Waals forces. This difference in trend between boiling and melting points arises because solid-state packing and intermolecular interactions affect melting behavior differently.

The answer is Option A: Both Statement I and Statement II are true.