Question

Which one of the following formulas represents an aldehyde? A. C2H5OH B. CH3COOH C. C6H10O5 D. C2H4O

Answer 1

The chemical formula that represents an aldehyde is C2H4O. The answer is letter C. CH3COOH is a carboxylic acid. C2H5OH is an alcohol and C6H10O5 is an ether. An aldehyde has an alkyl group with a fromyl group attached to it or –CHO.

Answer 2

Answer:

D. $C_2H_4O$

Explanation:

For this case, we have to keep in mind that the structure of the aldehyde has an oxo group (C=O) bonded to a  primary carbon. Therefore we have to search for this group in the options given.

For the first option, we have an OH group, so it is an alcohol. For B. we have an acid because the carboxylic acid group is present (COOH). For C. we have a very complex structure in which we have several oxo groups but neither is bonded to a primary carbon. In the last structure, we have the aldehyde group $C_2H_4O$ (see figure).