Question

Consider the complex ions, trans-${\left[\mathrm{Co}{\left(\mathrm{en}\right)}_2{\mathrm{Cl}}_2\right]}^{+}$ (A) and cis-${\left[\mathrm{Co}{\left(\mathrm{en}\right)}_2{\mathrm{Cl}}_2\right]}^{+}$ (B). The correct statement regarding them is

• A. Both (A) and (B) are optically active.
• B. (A) can be optically active, but (B) cannot be optically active.
• C. Both (A) and (B) cannot be optically active.
• D. (A) cannot be optically active, (B) can be optically active.

Answer 1

The correct option is D

(A) cannot be optically active, (B) can be optically active.

Explanation for correct option:

Option D: (A) cannot be optically active, (B) can be optically active

1. (A) is a trans complex it has a plane of symmetry, due to which it cannot be optically active.
2. (B) is a cis complex it does not have a plane of symmetry, so it is optically active.

Explanation for incorrect option:

Option A: Both (A) and (B) are optically active

• As (A) is a trans complex so it cannot be optically active.

Option B: (A) can be optically active, but (B) cannot be optically active

• As explained above due to the plane of symmetry (A) is not optically active but (B) is optically active.

Option C: Both (A) and (B) cannot be optically active

• As explained above due to the plane of symmetry (A) is not optically active but (B) is optically active.

Hence option D is correct, as complex (A) is not optically active but complex (B) is optically active.