JEE Main 2021 · 17 March · evening · Single correct · +4 / −1
Match List - I with List - II :
Choose the correct answer from the options given below :
| List - I | List - II | ||
|---|---|---|---|
| (a) | [Co(NH₃)₆][Cr(CN)₆] | (i) | Linkage isomerism |
| (b) | [Co(NH₃)₃(NO₂)₃] | (ii) | Solvate isomerism |
| (c) | [Cr(H₂O)₆Cl₃ | (iii) | Co-ordination isomerism |
| (d) | cis - [CrCl₂(ox)₂]³⁻ | (iv) | Optical isomerism |
- (a) (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
- (b) (a)-(iii), (b)-(i), (c)-(ii), (d)-(iv)
- (c) (a)-(ii), (b)-(i), (c)-(iii), (d)-(iv)
- (d) (a)-(iv), (b)-(ii), (c)-(iii), (d)-(i)
Answer and solution
Answer (b) (a)-(iii), (b)-(i), (c)-(ii), (d)-(iv)
Solution
Chemistry ma’am · 3 steps
For each complex, ask what can swap: the metals, the donor atom, the water, or the mirror image.
- Read each formula. Each type of isomerism needs one feature in the formula. Two complex ions means coordination isomerism. An ambidentate ligand means linkage isomerism. Water that can sit inside or outside the bracket means solvate isomerism. A chiral shape means optical isomerism.
List-I entry Feature to spot Isomerism (a) [Co(NH₃)₆][Cr(CN)₆] Both cation and anion are complexes, so the ligands can trade places, e.g. [Cr(NH₃)₆][Co(CN)₆] (iii) Coordination (b) [Co(NH₃)₃(NO₂)₃] NO₂⁻ is ambidentate: it binds through N (nitro) or O (nitrito) (i) Linkage (c) [Cr(H₂O)₆]Cl₃ Water can move out of the sphere, giving [Cr(H₂O)₅Cl]Cl₂.H₂O (ii) Solvate (hydrate) (d) cis-[CrCl₂(ox)₂]³⁻ Two chelating ox rings in the cis form leave no mirror plane (iv) Optical - Why cis is chiral. In the trans form the two Cl atoms sit opposite each other and a mirror plane passes through them. In the cis form that plane is lost, so the complex and its mirror image cannot be superimposed.
- So. The matching is (a)-(iii), (b)-(i), (c)-(ii), (d)-(iv), which is option (b).
The idea to keep. Match the isomerism to its fingerprint: two complex ions gives coordination, NO₂⁻, SCN⁻ or CN⁻ gives linkage, hydrated salts give solvate, and cis bis-chelates give optical.
Answer from the NTA final answer key. Solution by PrepWiser.