Question

Which of the following has the highest paramagnetism?

• A. $\left[Cr\right(H_{2}O{)}_6{]}^{3+}$
• B. $\left[Fe\right(H_{2}O{)}_6{]}^{2+}$
• C. $\left[Cu\right(H_{2}O{)}_6{]}^{2+}$
• D. $\left[Zn\right(H_{2}O{)}_6{]}^{2+}$

Answer 1

The correct option is B $\left[Fe\right(H_{2}O{)}_6{]}^{2+}$

Paramagnetism $\propto$ Number of unpaired electrons

In $\left[Cr\right(H_{2}O{)}_6{]}^{3+}$, Cr(III) has $3d^3$ outer electronic configuration with 3 unpaired electrons.

In $\left[Fe\right(H_{2}O{)}_6{]}^{2+}$, Fe(II) has $3d^6$ outer electronic configuration with 4 unpaired electrons.

In $\left[Cu\right(H_{2}O{)}_6{]}^{2+}$, Cu(II) has $3d^9$ electronic configuration with 1 unpaired electron.

In $\left[Zn\right(H_{2}O{)}_6{]}^{2+}$, Zn(II) has $3d^{10}$ electronic configuration with 0 unpaired electrons.

$\left[Fe\right(H_{2}O{)}_6{]}^{2+}$ has the highest paramagnetism as it contains a maximum number of unpaired electrons.

Hence, option $B$ is correct.