Q.The correct IUPAC name of the compound H3C-CH(Cl)-CH(CH3)-CH(CH3)-CH2-OH is

(a) $(CH_3)_3COH$ is 2-methylpropan-2-ol; (b) $C_6H_5CH_2OH$ is phenylmethanol (benzyl alcohol) by IUPAC nomenclature.

(a) $CH_3-C(CH_3)(OH)-CH_3$:

This structure has a central carbon bonded to three $CH_3$ groups and one $-OH$ group, i.e. $(CH_3)_3C-OH$ (tert-butyl alcohol). To name it by IUPAC rules:

• Select the longest carbon chain that includes the carbon bearing the $-OH$ group: here that chain is 3 carbons long (propane), since the central carbon is C2 of a propan-2-ol chain, and one of its three methyl groups is treated as a substituent (methyl) on that chain rather than as part of the main chain.
• Number the chain to give the $-OH$ group (the principal characteristic group, suffix '-ol') the lowest possible locant; here $C2$.
• The remaining methyl group attached to $C2$ is cited as a substituent prefix, '2-methyl'.

This gives the name 2-methylpropan-2-ol (molecular formula $C_4H_{10}O$), commonly known as tert-butyl alcohol or tert-butanol.

(b) Benzene ring with a $-CH_2-OH$ substituent: …