Question

Write the IUPAC name of the compound $\left(A\right)$ which is a $2-methyl$ alkane with the molecular mass of $72$.

Answer 1

Since it is an alkane $\left(C_n{H}_{2n+2}\right)$,
$\therefore 12n+2n+2=72$
The compound $\left(A\right)$ is $5C-atom$ alkane with $\left(Me\right)$ group at $C-2$. The structure of $\left(A\right)$ is as shown.