Answer the question on the basis of passage given below:
Transition metals form a large number of complexes or coordination compounds in which the metal atoms are bound to a number of anions or neutral molecules. The valence bond theory explains the formation, magnetic behaviour and geometrical shapes while the crystal field theory explains the effect of different crystal fields on the degeneracy of d-orbital energies of the central metal atom/ion. This provides for the quantitative estimation of orbital separation energies, magnetic moments and spectral and stability parameters.
The compound \([Pt(NH_3)_2Cl_2]\) exhibits:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Geometrical isomerism
\( \ce{[Pt(NH3)2Cl2]} \) is a square planar complex of the type [MX2L2]. The two Cl ligands can be on the same side (adjacent, cis) or on opposite sides (trans) of the square, giving two geometrical isomers: cis-platin and trans-platin.
Why the other options are incorrect
Option (2) Linkage isomerism — Incorrect. Needs an ambidentate ligand (\( \ce{NO2^{-}} \)/\( \ce{ONO^{-}} \), \( \ce{SCN^{-}} \)/\( \ce{NCS^{-}} \)) that can bind through two different atoms; \( \ce{NH3} \) and \( \ce{Cl^{-}} \) bind only one way.
Option (3) Ionisation isomerism — Incorrect. Arises when a counter ion outside the coordination sphere exchanges with a ligand inside, e.g. \( \ce{[Co(NH3)5SO4]Br} \) and \( \ce{[Co(NH3)5Br]SO4} \); this complex is neutral and has no counter ion.
Option (4) Coordination isomerism — Incorrect. Needs both cation and anion to be complex ions that exchange ligands, e.g. \( \ce{[Co(NH3)6][Cr(CN)6]} \); this is a single neutral complex.
NCERT (2026-27 edition):
Isomerism in Coordination Compounds – …
