Match List I with List II
| List I | List II |
| A. Geometrical Isomerism (cis) |  |
| B. Geometrical Isomerism (trans) |  |
| C. Geometrical Isomerism (facial) |  |
| D. Geometrical Isomerism (meridional) |  |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A-II, B-III, C-I, D-IV
In a square planar complex [MX2L2], the two identical ligands are cis when adjacent and trans when opposite. In an octahedral complex [Ma3b3], the isomer is facial (fac) when the three identical ligands occupy the corners of one octahedral face, and meridional (mer) when they lie around a meridian of the octahedron (two of them trans to each other).
A. Geometrical isomerism (cis) — This matches II. In \( \ce{[Pt(NH3)2Cl2]} \) structure II, the two Cl atoms are on the same side, at adjacent corners of the square.
B. Geometrical isomerism (trans) — This matches III. In structure III the two Cl atoms are at opposite corners of the square.
C. Geometrical isomerism (facial) — This matches I. In \( \ce{[Co(NH3)3(NO2)3]} \) structure I, the three \( \ce{NH3} \) groups are all adjacent (cis) to one another, on one face of the octahedron.
D. Geometrical isomerism (meridional) — This matches IV. In structure IV, two \( \ce{NH3} \) groups are trans to each other (top and bottom) and the third lies between them, along a meridian.
NCERT (2026-27 edition):
Geometric Isomerism – “… In a square planar complex of formula [MX2L2] (X and L are unidentate), the two ligands X may be arranged adjacent to each other in a cis isomer, or opposite to each other in a trans isomer.”
Geometric Isomerism – “… If three donor atoms of the same ligands occupy adjacent positions at the corners of an octahedral face, we have the facial (fac) isomer. When the positions are around the meridian of the octahedron, we get the meridional (mer) isomer.”