The electronic configuration $1s^2, 2s^2 2p^6, 3s^2 3p^6 3d^5, 4s^1$ represents:

Possible number of orientations of a subshell is

Which of the following statement$(s)$ is/are true?
$A$. If two orbitals have the same value of $(n+l)$,the orbital with lower value of $n$ will have lower energy.
$B$. Energies of the orbitals in the same subshell increase with increase in atomic number.
$C$. The size of $2p_x$ orbital is less than the size of $3p_x$ orbital.
$D$. Among $5f, 6s, 4d, 5p$ and $5d$ orbitals,none of the orbitals have $2$ radial nodes.

The five valence electrons of $_{15}P$ are represented as shown in the figure. If the spin quantum number of $B$ and $Z$ is $+1/2$,which of the following groups has three identical quantum numbers?

Beryllium's fourth electron will have the four quantum numbers :

The principal quantum number of an atom is related to the: