The cis isomer exist in two optical isomers. In the case of trans isomer optical isomerism not possible.
In octahedral complexes of the type \(M ( A )_4 X _2\) like \(\left[ Co \left( NH _3\right)_4 Cl _2\right]^{+}\)the optical isomerism is not possible.
[પ.ક્ર.: $Cr= 24,\,Mn= 25, \,Fe= 26, \,Co= 27$]