Question 71. Total number of ions from the following with noble gas configuration is.
\begin{aligned} & \mathrm{Sr}^{2+}(Z=38),\ \mathrm{Cs}^{+}(Z=55),\ \mathrm{La}^{2+}(Z=57),\ \mathrm{Pb}^{2+}(Z=82), \\ & \mathrm{Yb}^{2+}(Z=70)\ \text{and}\ \mathrm{Fe}^{2+}(Z=26) \end{aligned}Answer (2)
Explanation:
\quad Noble gas configuration =ns^{2} np^{6}
\begin{aligned} & [\mathrm{Sr}^{2+}] = [\mathrm{Kr}] \\ & [\mathrm{Cs}^{+}] = [\mathrm{Xe}] \\ & [\mathrm{Yb}^{2+}] = [\mathrm{Xe}]\,4f^{14} \\ & [\mathrm{La}^{2+}] = [\mathrm{Xe}]\,5d^{1} \\ & [\mathrm{Pb}^{2+}] = [\mathrm{Xe}]\,4f^{14}\,5d^{10}\,6s^{2} \\ & [\mathrm{Fe}^{2+}] = [\mathrm{Ar}]\,3d^{6} \end{aligned}