Which statement is false?

a. At equilibrium, equal amounts of products and reactants are present. ΔG° is a function of Keq.

b. When reactants become products, they do so through an intermediate transition state. Most biocatalysts are proteins.

The first statement is false: a. At equilibrium, equal amounts of products and reactants are present. ΔG° is a function of Keq.

Explanation:

When one part of a statement is false, the whole statement is false.

At equilibrium, the amounts of products and reactants does not have to be equal.

At equlibrium the rates of the forward reaction and the reverse reaction must be equal.

An equilibrium reaction may be represented by:

A + B ⇄ C + D

That represents two reactions:

Direct reaction: A + B → C + D (A and B yield C and D)

Reverse reaction: A + B ← C + D (C and D yield A and B: note that the arrow goes from right to left)

So, it is when the direct and the forward rates are equal that there is not net change in the amounts of all the species and so the reaction is is equilibrium).

As per the other statement, both parts are true:

When reactants become products, they do so through an intermediate transitrion state: when the reactants approach each other and collide with enough energy and appropiate position, the bonds start to break and the bonds of the products start to form. This is the transition state.

Most biocatalysts are proteins: enzymes are simply proteins, with specific structures, that may accelerate or even deceralate biochemical reactions.