Question

The correct order for the wavelength of absorption in the visible region is-

• A. $\left[Ni\right(N{O}_2{)}_6{]}^{4-}<\left[Ni\right(N{H}_3{)}_6{]}^{2+}<\left[Ni\right(H_{2}O{)}_6{]}^{2+}$
• B. $\left[Ni\right(N{O}_2{)}_6{]}^{4-}<\left[Ni\right(H_{2}O{)}_6{]}^{2+}<\left[Ni\right(N{H}_3{)}_6{]}^{2+}$
• C. $\left[Ni\right(H_{2}O{)}_6{]}^{4-}<\left[Ni\right(N{H}_3{)}_6{]}^{2+}<\left[Ni\right(N{O}_2{)}_6{]}^{4-}$
• D. $\left[Ni\right(N{H}_3{)}_6{]}^{2+}<\left[Ni\right(H_{2}O{)}_6{]}^{2+}<\left[Ni\right(N{O}_2{)}_6{]}^{4-}$

Answer 1

The correct option is A $\left[Ni\right(N{O}_2{)}_6{]}^{4-}<\left[Ni\right(N{H}_3{)}_6{]}^{2+}<\left[Ni\right(H_{2}O{)}_6{]}^{2+}$

Stronger is the ligand, greater will be the crystal field splitting and lower will be the wavelength of light absorbed.

The increasing order of the crystal field splitting(as per the ligand strength according to spectrochemical saries) is $H_{2}O<N{H}_3<N{O}_2$

Correct order for the wavelength of absorption in the visible region is

$\left[Ni\right(N{O}_2{)}_6{]}^{4-}<\left[Ni\right(N{H}_3{)}_6{]}^{2+}<\left[Ni\right(H_{2}O{)}_6{]}^{2+}$

Hence, option (a) is correct.