The complex ion \([Co(en)_2Cl_2]^+\) has an octahedral geometry. However, it shows only two geometrical isomers:
This refutes the assertion that it shows three geometrical isomers. Thus, (A) is incorrect. However, the reason (R) stating that the complex has an octahedral geometry is true.
Final Answer: (3) (A) is not correct but (R) is correct.
Draw the possible isomers of:
\[ [ \text{Co}(\text{en})_2\text{Cl}_2 ]^+ \]
Let \( S = \left\{ m \in \mathbb{Z} : A^m + A^m = 3I - A^{-6} \right\} \), where
\[ A = \begin{bmatrix} 2 & -1 \\ 1 & 0 \end{bmatrix} \]Then \( n(S) \) is equal to ______.