17. An increase in a transition state's energy necessarily requires (A) An increase in the rate of the reaction (B) An increase in the rate of that particular step of the reaction (C) A decrease in the rate of the reaction (D) A decrease in the rate of that particular step of the reaction 18. Choose the most stable carbocation (A) (B) (C) (D) 19. Molecule A is formed through a SN2 reaction. Which pair of reactants would give the highest yield of molecule A? (A) (CH3)3CBr and CH3CH2CH2CH2O (B) (CH3)3COand CH3CH2CH2CH2Br (C) SN1 not possible (D) None of the above