Magnetic moment $2.83\text{BM}$ is given by which of the following ions? (At. no. $\text{Ti}=22,\text{Cr}=24,\text{Mn}=25,\text{Ni}=28$)

Magnetic moment $\mu =\sqrt{n(n+2)}\text{BM}$, where $n$ is the number of unpaired electrons.For $\mu =2.83\text{BM}\approx \sqrt{8}$, $n$ must be $2$.${\text{Ti}}^{3+}$ ($d^1$): $n=1$${\text{Ni}}^{2+}$ ($d^8$): $n=2$ (since $8$ electrons fill as $\uparrow \downarrow \uparrow \downarrow \uparrow \downarrow \uparrow \uparrow$)${\text{Cr}}^{3+}$ ($d^3$): $n=3$${\text{Mn}}^{2+}$ ($d^5$): $n=5$ The ion with $2$ unpaired electrons is ${\text{Ni}}^{2+}$.