Lowest locant is given to the double bond (ene). Numbering from the alkene end makes the double bond at C-1 and places chloro at C-3.
(b) \( \mathrm{CH_3-CH(OH)-COOH} \)
Answer: 2-hydroxypropanoic acid
Parent acid: propanoic acid (\(\mathrm{COOH}\) has highest priority). The hydroxyl substituent is at C-2. (Common name: lactic acid.)
(c) A three-carbon chain \( \mathrm{CH_2-CH-CH_2} \) with an ethyl group on each carbon.
Answer: 4-ethylheptane
Choose the longest chain passing from left ethyl → \( \mathrm{CH_2-CH-CH_2} \) → right ethyl: this gives a 7-carbon parent (heptane). The remaining ethyl becomes a substituent at the central carbon (C-4) → 4-ethylheptane.
(d).
Answer: bromochloroiodomethane
Single-carbon parent: methane. Three halo substituents are listed in alphabetical order: bromo, chloro, iodo. (Locants are all 1; writing 1-bromo-1-chloro-1-iodomethane is acceptable.)
.