Question

Which of the following compounds has $- OH$ as a functional group?
A. Butanone
B. Butanol
C. Butanoic acid
D. Butanal

Answer 1

We know that the concept of functional group is very important in organic chemistry because it determines the chemical reactions the compound will undergo. $- OH$ is also known as hydroxyl group . It contains one oxygen atom and one hydrogen atom.

Complete answer:
We know that the ketone functional group contains ${R_2}C = O$group, the suffix of ketone is $- one$.Both the $R$ connected to the carbon atom of the ketone are alkyl or aryl. The carboxylic acid functional group contains $COOH$group, the suffix of carboxylic acid is $- oic$ $acid$.The aldehyde functional group contains $C = O$. The carbon atom has two more bonds out of which one is hydrogen and other can be hydrogen or aryl or alkyl group. The suffix of aldehyde is $- al$.The alcohol functional group contains $- OH$.The suffix of the alcohol group is $- ol$.
In the question we are given that we have to identify the compound which contains $- OH$ as a functional group. If a compound has $- OH$ as a functional group the compound is alcohol.
Let us check one by one. Butanone has the suffix $- one$ so it is a ketone . Butanol has a suffix of $- ol$, so it is an alcohol . It will contain $- OH$as a functional group. Butanoic acid has a suffix of $- oic$ $acid$, it is carboxylic acid so it will contain $COOH$. Butanal has a suffix of $- al$, so it will be an aldehyde.
So from the above explanation it is clear to us that butanol is an alcohol which will contain $- OH$ as a functional group.

So the correct answer to the given question is option: B. Butanol.

Note:
Some more functional are amines having general formula $R - N{H_2}$. They can be categorised as ${1^ \circ },{2^ \circ }$ and ${3^ \circ }$ amines depending upon the number of alkyl groups attached to amines. If there is one alkyl group attached then it is ${1^ \circ }$, if there are two alkyl group attached then it is ${2^ \circ }$ and if there are three alkyl group attached then it is ${3^ \circ }$.