VITEEE 2012 Paper

Since alkyl group has + I - effect and aryl group has + R - effect, Hence greater the number of alkyl and aryl groups attached to the carbonyl group, its reactivity towards nucleophilic addition reaction. Secondly, as the steric crowding on carbonyl group increases, the reactivity decreases accordingly.
∴ Correct reactivity order for reaction with PhMgBr is