**Assertion (A):** In the Swarts reaction, AgF converts RBr to RF. **Reason (R):** AgBr (formed as byproduct) is insoluble and precipitates, driving the reaction toward RF formation.

**Assertion (A):** The SN2 reaction of (R)-2-bromobutane with NaOH gives (S)-butan-2-ol. **Reason (R):** In SN2, the nucleophile attacks from the side opposite to the leaving group (backside attack), leading to Walden inversion of configuration.

**Assertion (A):** SN1 reactions of chiral substrates give racemic mixtures. **Reason (R):** The planar sp2 carbocation intermediate in SN1 is equally accessible to nucleophilic attack from both faces.

**Assertion (A):** Chlorobenzene requires much harsher conditions (623 K, 300 atm) than chloroethane for nucleophilic substitution with NaOH. **Reason (R):** In chlorobenzene, the lone pair on Cl donates electrons into the benzene ring by resonance, giving the C-Cl bond partial double bond character and making it shorter and stronger.

The C-I bond (214 pm, 213 kJ/mol) compared to the C-F bond (135 pm, 485 kJ/mol) is: