Question

Which has maximum paramagnetic nature?

• A. $[Fe(CN{)}_6{]}^{4-}$
• B. $[Cu(H_{2}O{)}_4{]}^{2+}$
• C. $[Zn(N{H}_3{)}_4{]}^{2+}$
• D. $[Mn(H_{2}O{)}_6{]}^{2+}$

Answer 1

Answer: (D)

Paramagnetic character $\propto$ number of unpaired electrons
(a) ${\left[Fe(CN{)}_6\right]}^{4-}$ Iron is in $+2$ oxidation state.

There is no unpaired electron in ${\left[Fe(CN{)}_6\right]}^{4-}$. So, it is diamagnetic.
(b) ${\left[Cu{\left(H_{2}O\right)}_4\right]}^{2+}$ Copper is in $+2$ oxidation state.

There is one unpaired electron. So, it is paramagnetic.
(c) ${\left[Zn{\left(N{H}_3\right)}_4\right]}^{2+}$ zinc is in $+2$ oxidation state.

There is no unpaired electron. So, it is diamagnetic.
(d) ${\left[Mn{\left(H_{2}O\right)}_6\right]}^{2+}Mn$ is in $+2$ oxidation state.

In ${\left[Mn{\left(H_{2}O\right)}_6\right]}^{2+}$ there are five unpaired electrons. So, it has maximum paramagnetic character.