The Cl–Co–Cl bond angle values in a fac-[Co(NH3)3Cl3] complex is/are:

🧠 fac Means All Three on One Face

In an octahedron, the fac (facial) isomer of $\mathrm{[MA_3X_3]}$ has the three identical X ligands on one triangular face — every X–M–X angle is 90°.

The mer (meridional) isomer has the three X on a meridian (a great-circle arc), giving two cis pairs (90°) and one trans pair (180°).

🗺️ fac-$[\mathrm{Co(NH_3)_3Cl_3}]$ Geometry

Place the three Cl on the top, front, and right faces of an octahedron. Every pair of these Cl is at 90° to one another (they all share an edge of the octahedron). Cl–Co–Cl = 90° for every pair.

So the only Cl–Co–Cl angle present is 90°.

⚡ The "fac vs mer Angles" Lookup

| Isomer | X–M–X angles | |---|---| | fac | only 90° | | mer | 90° (×2 pairs), 180° (×1 pair) |

For the fac isomer, all three identical-ligand pairs are cis to each other.

⚠️ Don't Mix In 120° or 180°

In an octahedron, ligand–metal–ligand angles are only 90° (cis) or 180° (trans). 120° doesn't appear in octahedral geometry — that's a trigonal bipyramidal angle. Reject options (1) and (4) on geometry alone.

$\boxed{\text{Answer: (2) 90°}}$