The valence shell of calcium contains

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 $2$.

The maximum number of electrons in a subshell of an atom is determined by which of the following expressions?

The number of orbitals in $2p$ sub-shell is

The configuration $1s^2 2s^2 2p^5 3s^1$ shows:

Identify the elements represented by the following electronic configurations:
$(a)$ $[He] \, 2s^1$
$(b)$ $[Ne] \, 3s^2 \, 3p^3$
$(c)$ $[Ar] \, 4s^2 \, 3d^1$