Question

What are all the functional groups in penicillamine?

Answer 1

Three different functional groups.

Explanation:

On the image above the three different functional groups are highlighted.

Here we have an amine group `-NH_2` (Green).

Here there is a Thiol group `-SH` (Blue)

and at last there are an carboxylic acid group `-COOH` (Yellow)

Then there are two methyl groups `-CH_3`. But those are normally not considered as "functional groups".