Among Co^3+, Ti^2+, V^2+ and Cr^2+ ions, one if used as a reagent cannot liberate H_2 from dilute mineral acid solution, its spin-only magnetic…

Among $\displaystyle \mathrm{Co}^{3+}, \mathrm{Ti}^{2+}, \mathrm{V}^{2+}$ and $\displaystyle \mathrm{Cr}^{2+}$ ions, one if used as a reagent cannot liberate $\displaystyle \mathrm{H}_2$ from dilute mineral acid solution, its spin-only magnetic moment in gaseous state is \_\_\_\_ B.M. (Nearest integer)