Question

Identify the correct decreasing order of boiling point for hydrides of halogens.

• A. \(\mathrm{HF}>\mathrm{HCl}>\mathrm{HBr}>\mathrm{HI}\)
• B. \(\mathrm{HI}>\mathrm{HBr}>\mathrm{HCl}>\mathrm{HF}\)
• C. \(\mathrm{HF}>\mathrm{HI}>\mathrm{HBr}>\mathrm{HCl}\)
• D. \(\mathrm{HI}>\mathrm{HF}>\mathrm{HBr}>\mathrm{HCl}\)

Hint:

HF is highest because of hydrogen bonding; the rest follow molecular size and van der Waals forces.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept
Boiling point depends on hydrogen bonding and on van der Waals forces, which grow with molecular size.

Step 2: HF
HF forms strong intermolecular hydrogen bonds, so it has the highest boiling point.

Step 3: Others
For HCl, HBr and HI there is no hydrogen bonding, so the boiling point rises with size: \( \text{HI}>\text{HBr}>\text{HCl} \).

Step 4: Compare the options
The order is \( \text{HF}>\text{HI}>\text{HBr}>\text{HCl} \), option (C).

Final Answer:
The order of boiling points is HF > HI > HBr > HCl. \[ \boxed{\text{(C) }\mathrm{HF}>\mathrm{HI}>\mathrm{HBr}>\mathrm{HCl}} \]