The number of $s$-electrons present in an ion with $55$ protons in its unipositive state is

From the following sets of quantum numbers,which set is possible?

The probability of finding electrons in $d_{xy}$ orbital is

If $n$ and $l$ represent the principal and azimuthal quantum numbers respectively,the formula used to determine the number of radial nodes possible for a given orbital is:

Identify the correct statements:
a) In an atom,the maximum number of electrons with $n=4$ and $m_s=+\frac{1}{2}$ is $16$.
b) There are $4$ subshells associated with $n=5$.
c) $n=2, l=1, m_l=0$ and $m_s=-\frac{1}{2}$ is a possible set of quantum numbers.
d) The number of radial nodes for $3s$ orbital is $2$.

Which electronic configuration represents a noble gas?