Question

Assertion (A): Following reaction proceed better with KF than with NaF. $R_3-C-Cl+MF\to R_3-C-F+MCl$
Reason (R) : K is more reactive than Na.

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

Answer 1

Answer: (B)

Both Assertion and Reason are true but Reason is not a correct explanation of Assertion

In this reaction, KF is more reactive than NaF. This is due to lower lattice energy of KF than that of NaF. The lattice energy is inversely proportional to the ionic size. $K^{+}$ ion has higher ionic size than $N{a}^{+}$ ion.