The first mechanistic step in the direct reaction of an amine with a carboxylic acid to produce an amide is . A) an acid-base reaction
B) nucleophilic attack on the carbonyl carbon
C) loss of H2O
D) loss of CO2
E) loss of N2

The first step is - option A) an acid base reaction.

Explanation:

The direct reaction of a carboxylic acid with an amine to form an amide is expected to be difficult as it would deprotonate the carboxylic acid and make a nonreactive carboxylate.

The first step in this reaction would be an acid - base reaction as protonation of the carbonyl carbon, that involves the interchange of proton in between electric charge or neutral compound, it is also known as protonation or deprotonation. The acid base reaction is followed by the nucleophilic attack on the carbonyl carbon.

Thus, The first step is - option A) an acid base reaction.

The correct answer among the choices listed above is option B. The type of coolant usually used to remove heat from a nuclear reactor core is liquid sodium or water. Nuclear power plants are usually found near bodies of  water because they utilize the water in these area as coolants for the processes involved.