Question

Examine the relation between the following pairs of compounds.

• A. All I, II, III are identical
• B. All I, II, III are isomers
• C. I, II are identical, III are positional isomers
• D. I is identical and II, III are isomers

Answer 1

The correct option is C I, II are identical, III are positional isomers

In (I), both compound have same molecular formula and they same position of Cl atom. Both Cl are in 1, 2 (ortho) position in both the compounds so they are identical.
In (II), both compound have same molecular formula and same position of OH group. Both OH are in 1, 3 ( meta ) position in both compound so they are identical.
In (III), we have same molecular formula but the position of COOH group is different. One is para (1, 4) and another one is meta (1, 3) so they are positional isomers.
Hence, the correct option is (c).