Which of the following does not correctly describe sn2 reactions of alkyl halides? a) the mechanism consists of a single step with no intermediates. b) tertiary halides react faster than secondary halides. c) the transition state species has a pentavalent carbon atom. d) rate of reaction depends on the concentrations of both the alkyl halide and the nucleophile.

The correct answer is B the tertiary halides reacts faster than primary halides.

Explanation:

During SN2 reaction the nucleophile attack the alkyl halide from the opposite side resulting in the formation of transition state in which a bond is not completely broken or a new bond is not completely formed.

   After a certain period of time the nucleophile attach with the substrate by substituting the existing nuclophile.

  An increase in the bulkiness in the alkyl halide the SN2 reaction rate of that alkyl halide decreases.This phenomenon is called steric hindrance.

  So from that point of view the that statement tertiary halides reacts faster that secondary halide is not correct.

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)