Question

Choose the response that matches the correct functional group classification with the following group of structural formula:
    

(A) Anhydride, Lactam, Lactone
(B) Lactam, Imide, Lactone
(C) Imide, Lactone, Anhydride
(D) Imide, Lactam, Lactone

Answer 1

Hint: Before solving the question try to understand the terms given in the options. Form or visualize a basic structure of the given functional groups and then attempt solving the question.

Complete answer:
We will follow the hint given to us to arrive at the final answer. Let us now understand the functional groups given in the options and form a basic structure to enhance our knowledge as well as solve the question at hand.
Functional Groups:
> Anhydride: The compound formed from other compounds by dehydration i.e. after removal of water is called an anhydride.

Structure:
                              

Where, $R_1$ and $R_2$ are alkyl groups.
> Lactam: A lactam also called cyclic amide is an amide in the molecule of which there are one or two carbon chains connecting the carbonyl carbon to the nitrogen atom.
Structure:

                          

> Lactone: A lactone is an ester in which the functional group i.e. the ester becomes part of the ring structure with the present carbon atoms.
Structure:

                             

> Imide: A functional group having a nitrogen atom bonded to two carbonyl groups, or a molecule containing this functional group.
Structure:
                            

From the above definitions and structures, we can now solve the question without any problem.
> The structure of the first functional group given in the question resembles the structure of Imide, Hence the first functional group is Imide.
> The structure of the second functional group in the question obeys the definition and structure of Lactam, Hence the second functional group is Lactam.
> The structure of the third functional group given in the question resembles the structure of Lactone, Hence the first functional group is Lactone.

Therefore, the correct answer is option (D).

Note: At times students get confused between a lactam and lactone as they might sound similar. To prevent this confusion always form a clear image of the functional group as it will help you distinguish between similar sounding functional groups.