Match List-I with List-II

List-I (Column A)	List-II (Column B)
(A) n-hexadecanoic acid	(I) Watson and Crick
(B) Secondary amino group	(II) Proline
(C) Double helical DNA	(III) Palmitic acid
(D) Enantiomer	(IV) Optical isomer

Choose the correct answer from the options given below:

Correct option is D

Explanation of the Correct Option (d): (A)-(III), (B)-(II), (C)-(I), (D)-(IV)
(A) n-hexadecanoic acid → (III) Palmitic acid
· n-Hexadecanoic acid is the systematic (IUPAC) name of palmitic acid.
· It is a saturated fatty acid with 16 carbon atoms (C₁₆:₀).
(B) Secondary amino group → (II) Proline
· Proline is unique among amino acids.
· Its amino group is secondary because it is part of a cyclic structure.
(C) Double helical DNA → (I) Watson and Crick
· The double helix structure of DNA was proposed by Watson and Crick in 1953.
(D) Enantiomer → (IV) Optical isomer
· Enantiomers are non-superimposable mirror images.
· They are also called optical isomers because they rotate plane-polarized light.
Explanation of Other Options
Option (a)
· Incorrect because:
· n-hexadecanoic acid is not related to Watson and Crick.
Option (b)
· Incorrect due to wrong matching of amino group and DNA.
Option (c)
· Incorrect because:
· Enantiomer refers to optical isomer, not palmitic acid.
Key Points Related to the Question
· Palmitic acid = n-hexadecanoic acid
· Proline = only amino acid with secondary amino group
· Watson & Crick = DNA double helix model
· Enantiomers = optical isomers