Total number of ions from the following with noble gas configuration is . . . . . . .
$Sr^{2+} (Z=38), Cs^{+} (Z=55), La^{2+} (Z=57), Pb^{2+} (Z=82), Yb^{2+} (Z=70) \text{ and } Fe^{2+} (Z=26)$

Explain,giving reasons,which of the following sets of quantum numbers are not possible.
$(a)$ $n=0, l=0, m_{l}=0, m_{s}=+\frac{1}{2}$
$(b)$ $n=1, l=0, m_{l}=0, m_{s}=-\frac{1}{2}$
$(c)$ $n=1, l=1, m_{l}=0, m_{s}=+\frac{1}{2}$
$(d)$ $n=2, l=1, m_{l}=0, m_{s}=-\frac{1}{2}$
$(e)$ $n=3, l=3, m_{l}=-3, m_{s}=+\frac{1}{2}$
$(f)$ $n=3, l=1, m_{l}=0, m_{s}=+\frac{1}{2}$

The azimuthal quantum number for the last electron of the $Na$ atom is:

The total maximum number of electrons possible in $3d$,$6d$,$5s$,and $4f$ orbitals with $m_l$ (magnetic quantum number) value $-2$ is

Which rule is violated in the given electronic configuration?

$Ge$ $(Z=32)$ in its ground state electronic configuration has $x$ completely filled orbitals with $m_{l}=0$. The value of $x$ is ..... .