Q3. Give the IUPAC names of (i) CH3CH2CH(CH3)COOH, (ii) HOOC–CH2–CH2–COOH, (iii) C6H5CH2CH2CH2COOH.
(i) 2-Methylbutanoic acid. (ii) Butanedioic acid (succinic acid). (iii) 4-Phenylbutanoic acid: the phenyl group is on C4, counting the COOH carbon as C1 (reasoned from NCERT page 244 and Table 8.3).
Q4. Write the structures of malonic acid and adipic acid and give their IUPAC names.
Malonic acid, HOOC–CH2–COOH, propanedioic acid; adipic acid, HOOC–(CH2)4–COOH, hexanedioic acid (NCERT Table 8.3, page 244).
Q5. What are fatty acids, and in what form do they occur in natural fats?
Aliphatic monocarboxylic acids associated with fats, oils or waxes; in natural fats they occur chiefly as glycerol esters. NCERT highlights common C12–C18 members, but the IUPAC definition is not limited to that range.
Q6. What are the bond angles round the carboxyl carbon, and why?
About 120°, with all three bonds in one plane (NCERT page 245), as for any sp2 carbon with three σ bonds (reasoned).