JEE Main 2026 — 28 January, Evening Shift — Question 69

The number of isoelectronic species among $\mathrm{Sc}^{3+}$, $\mathrm{Cr}^{2+}, \mathrm{Mn}^{3+}, \mathrm{Co}^{3+}$ and $\mathrm{Fe}^{3+}$ is ' n '. If ' n ' moles of AgCl is formed during the reaction of complex with formula $\mathrm{CoCl}_{3}(\mathrm{en})_{2} \mathrm{NH}_{3}$ with excess of $\mathrm{AgNO}_{3}$ solution, then the number of electrons present in the $t_{2 g}$ orbital of the complex is $\_\_\_\_$。