c
\(\left( Ti ^{+3}\left( H _2 O \right)_6\right)^{3+}\)

\(Ti ^{+3}: 3 d ^1\)

\(C.F.S.E.\) \(=-0.4 \times \Delta_0\)

\(=-\frac{96 \times 10^3}{ N _0}\,J\)

\(\Delta_0=\frac{96 \times 10^3}{0.4 \times 6 \times 10^{23}}\)

\(\frac{ hc }{\lambda}=\frac{96 \times 10^3}{0.4 \times 6 \times 10^{23}}\)

\(\lambda=\frac{0.4 \times 6 \times 10^{23} \times 6.4 \times 10^{-34} \times 3 \times 10^8}{96 \times 10^3}\)

\(=0.48 \times 10^{-6}\,m\)

\(=480 \times 10^{-9}\,m\)

\(=480\,nm\)