Question

Which of the following has an aldehyde functional group?
(A) $R - COOH$
(B) $R - CHO$
(C) $R - CO - R$
(D) $R - COO - R$
(E) $R - CO - N{H_2}$

Answer 1

To solve this question, we must first understand the basics of the aldehyde functional group. Then we need to assess the chemical formula representation of Aldehydic groups and then only we can conclude the correct answer.

Complete answer:

Before we move forward with the solution of this given question, let us first understand some basic concepts: Aldehydes incorporate a carbonyl functional group, $C = O$ . They are organic compounds with structures $- CHO$.

Use of Aldehydes:
1. Formaldehyde is a gas. With $40\%$ solution in water, it forms Formalin which is used in preserving biological specimens.
2. Formaldehyde is used in embalming, tanning, preparing glues and polymeric products, as germicides, insecticides, and fungicides for plants. It is also used in drug testing and photography.
3. When reacted with phenol, formaldehyde forms Bakelite, which is used in plastics, coatings, and adhesives.
4. Acetaldehyde is largely used for the production of acetic acid and pyridine derivatives.
5. Benzaldehyde is used in perfumes, cosmetic products, and dyes. It is added to provide almond flavour to food products and also used as a bee repellent.

So, from the above explanation we can conclude that the compound containing $- CHO$ group, will be our required answer.

So, clearly we can conclude that the correct answer is Option (B).

Note: In aldehydes, the carbonyl group has one hydrogen atom attached to it together with either a $2nd$ hydrogen atom or a hydrogen group which may be an alkyl group or one containing a benzene ring. The carbonyl carbon of an aldehyde has a hydrogen atom attached to it whereas that of a ketone is attached to two alkyl or aryl groups. The C-H bond in aldehydes makes them easily oxidizable (they are strong reducing agents).