(A) IUPAC name of the compound is 3-Ethyl-5-methylhexane-2,4-diol.

Here, the –OH groups are the functional groups. The number of carbon atoms in the longest chain is 6 and all the bonds between the carbon atoms are single bonds. So, the IUPAC name of the longest carbon chain is Hexane. The counting of the position starts from the right-hand side so that all the substitute groups get the lowest position numbers. Two–OH groups are attached to the carbon atoms at2^nd and 4^thpositions, one methyl group at 5^th position and one ethyl group are attached to the 3^rd position. Therefore, the IUPAC name of the above compound is 3-Ethyl-5-methylhexane-2,4-diol.

(B)

IUPAC name of the compound is1-Methoxy-3-nitrocyclohexane.

The number of longest carbon atoms in a chain in the above structure is 6 and they in present in a cyclic manner. All the bonds between the carbon atoms are single bonds. So, the IUPAC name of the longest carbon chain is cyclohexane. Among nitro and methoxy groups,methoxy is written first, then nitro. Therefore, the IUPAC name of the above compound is 1-Methoxy-3-nitrocyclohexane.