Which complex is optically active?
[Co(en)2Cl₂]+ (octahedral) can form a trans isomer (symmetric) and a cis isomer (chiral, non-superimposable), showing optical isomerism.
Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Isomerism - Optical Isomerism and Linkage Ionisation Solvate