Question

Which of the following statements are incorrect about isopentane?
A.It has three $C{H_3}$ groups
B.It has one $C{H_2}$ group
C.It has one $CH$ group
D.It has the carbon which is not bonded with the hydrogen

Answer 1

Isopentane is the alkane which is made by putting the value of $n$ as 5 in its general formula, ${C_n}{H_{2n + 2}}$. So, the formula of isopentane is ${C_5}{H_{12}}$. It has five carbon atoms and twelve hydrogen atoms. Isopentane is also known as methyl butane.

Complete Step by step answer: Alkanes are organic compounds having carbon and hydrogen atoms bonded with a single bond. The general formula of alkanes is ${C_n}{H_{2n + 2}}$. The simplest family of compounds is called alkanes. These types of compounds contain only carbon and hydrogen. Each carbon atom forms four bonds and each hydrogen atom forms one bond. In the general formula of alkanes, ${C_n}{H_{2n + 2}}$, when we put the value of $n$ as 5, we get, ${C_5}{H_{12}}$, which is known as isopentane as it has five carbons.
Isopentane can also be called methyl – butane and 2 – methyl butane. It is the branched chain saturated hydrocarbon having five carbon atoms. It is an extremely volatile and extremely flammable liquid at room temperature and pressure. The structure of isopentane can be made as –

From the structure of isopentane, we can conclude that it has three $C{H_3}$ groups, one $C{H_2}$ group and one $CH$ group. Hence, the options (A), (B) and (C) are correct about isopentane. While in the option (D) is said that there is the carbon which is not bonded with the hydrogen. So, in the structure we can see that there is no carbon which is not bonded with the hydrogen. Hence, option (D) is incorrect about the isopentane.

Therefore, the correct option is (D).

Note: The traditional name isopentane was still retained in the 1993 IUPAC recommendations, but is no longer recommended according to the 2013 recommendations. The preferred IUPAC name is the systematic name 2-methylbutane.