Question

Among the following ions which one 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. $\left[Zn\right(H_{2}O{)}_4{]}^{2+}$

Answer 1

Answer: (B)

$\left[Fe\right(H_{2}O{)}_6{]}^{2+}$

As we know,
magnetic moment
$\mu =\sqrt{n(n+2)}$ BM
n = no of unpaired electron so
higher no of unpaired electron will have higher moment.
$\left[Cr\right(H_{2}O{)}_6{]}^{3+}$
+ 3 n =3
$\left[Fe\right(H_{2}O{)}_6{]}^{2+}$
+2 n = 4 highest
$\left[Cu\right(H_{2}O{)}_6{]}^{2+}$
+2 n=1
$\left[Zn\right(H_{2}O{)}_4{]}^{2+}$
+2 n = 0