Question

The functional group present in propanal is ___________.

• A. $-OH$
• B. $-COOH$
• C. $-CO-$
• D. $-CHO$

Answer 1

The correct option is D

$-\mathrm{CHO}$

Explanation for the correct option:

(D).

• A functional group is a set of atoms in a molecule that have specific chemical properties independent of the other atoms in the molecules.
• Functional group aldehyde has the general formula $\mathrm{R}-\mathrm{CHO}$.
• The molecular formula of propanal is ${\mathrm{CH}}_3-{\mathrm{CH}}_2-\mathrm{CHO}$. So, the functional group present in propanal is $-\mathrm{CHO}$.

Explanation for the incorrect options:

(A) $-\mathrm{OH}$ is the functional group of alcohol. For example, ethanol $\left({\mathrm{C}}_2{\mathrm{H}}_5-\mathrm{OH}\right)$.

(B) $-\mathrm{COOH}$ is the functional group of carboxylic acid. For example, ethanoic acid $\left({\mathrm{CH}}_3-\mathrm{COOH}\right)$.

(C) $-\mathrm{CO}-$ is the ketone functional group. For example, propanone $\left({\mathrm{CH}}_3-\mathrm{CO}-{\mathrm{CH}}_3\right)$

Hence, option (D) is correct. The functional group present in propanal is $-\mathrm{CHO}$.