Question

The first member of $RCOOH$ is
A. acetic acid
B. formic acid (HCOOH)
C. butyric acid
D. none of the above

Answer 1

The hydrocarbons are the organic compound formed from an only hydrogen atom and a carbon atom. The hydrocarbon group for alkane starts with methane containing only a single carbon atom and ends with a decane containing ten carbon atoms.

Complete step by step answer:
Functional groups are the specific group of hydrocarbons attached to the compound which is responsible for its reaction with other compounds. Groups having the same functional group show the same chemical reaction.
A carboxylic acid is one of the functional groups in which the carboxyl group is attached to the alkyl group. In this group, the carbon atom is joined with one oxygen atom by a double bond and with one hydroxyl group by a single bond. The general formula of carboxylic acid is $R - COOH$. In this R is the alkyl group and –COOH is the carboxyl group.
The first member of $R - COOH$ group is a methanoic acid-containing single carbon atom. The general formula for methanoic acid is HCOOH.
The arrangement of hydrocarbons in any functional group depends on the number of carbon atoms present.
Methanoic acid is also known as formic acid. The formic acid is the IUPAC name of HCOOH and methanoic acid is the systematic name.
Therefore, the correct option is B.

Note:
Formic acid (HCOOH) is also named as formate. It is a weak acid thus it behaves as a weak electrolyte. The common molecular formula for function group carboxylic acid is ${C_n}{H_{2n + 1}}COOH$.