The ortho/para directing group among the following is:A)COOHB) CNC)COC{H_3}.D) NHCOC{H_3}

The ortho/para directing groups in organic chemistry are groups that direct incoming electrophilic substitutions to the ortho (adjacent) and para (opposite) positions on an aromatic ring. These groups typically contain lone pairs of electrons that can be delocalized into the aromatic ring, increasing electron density at those positions.

Let's analyze the options you provided:

A) COOH - The carboxylic acid group (COOH) is an ortho/para directing group. It contains a lone pair on the oxygen atom, which can be delocalized into the aromatic ring, directing electrophilic substitution to the ortho and para positions.

B) CN - The cyano group (CN) is a meta directing group. It does not contain a lone pair that can be delocalized into the ring, and it actually withdraws electron density from the ring, making it a meta director.

C) COCH3 - The acetyl group (COCH3) is also a meta directing group for similar reasons as the cyano group. It withdraws electron density from the ring.

D) NHCOCH3 - This group also contains a carbonyl group (CO) and is a meta directing group.

So, among the options provided, A) COOH is the only ortho/para directing group.