Question

Assertion (A): The boiling points of alkyl halides decrease in the order: RI>RBr>RCl>RF. 
Reason (R): The boiling points of alkyl chlorides, bromides and iodides are considerably higher than that of the hydrocarbon of comparable molecular mass.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false, but Reason (R) is true.

Hint:

Boiling points of alkyl halides are influenced by the size of the halogen and the intermolecular forces present.

Answer 1

The Correct Option is C

Boiling Point Order of Alkyl Halides 

Step 1: Understanding the boiling point order. The boiling points of alkyl halides decrease in the order: \( \text{RI} > \text{RBr} > \text{RCl} > \text{RF} \) because the iodine atom is the largest halogen, leading to stronger dispersion forces and, consequently, higher boiling points.

Step 2: Reason for the boiling point order. While Reason (R) is true in stating that alkyl halides have higher boiling points compared to hydrocarbons of comparable molecular mass, it does not directly explain the order in which boiling points decrease. The reason for this specific order lies more in the halogen size and the resultant intermolecular forces.

Step 3: Conclusion. Thus, both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A). The correct answer is option (B).