Write the ground-state electronic configuration of chromium

Chromium $(Z=24)$ is an exception to the usual filling order. Its ground-state configuration is: $\mathrm{Cr}: 1s^2\,2s^2\,2p^6\,3s^2\,3p^6\,3d^5\,4s^1$ or $[\mathrm{Ar}]\,3d^5\,4s^1$

Relate azimuthal quantum number $l$ to subshell type

• For $s$-subshell, $l=0$
• For $p$-subshell, $l=1$
• For $d$-subshell, $l=2$

Count electrons with $l=1$

Electrons with $l=1$ are all the electrons in $p$-subshells.

Present $p$-subshells in chromium ground state:

• $2p^6$ gives $6$ electrons
• $3p^6$ gives $6$ electrons

Total with $l=1$: $6+6=12$

Count electrons with $l=2$

Electrons with $l=2$ are all the electrons in $d$-subshells.

Present $d$-subshell in chromium ground state:

• $3d^5$ gives $5$ electrons

Total with $l=2$: $5$

Match with options

Hence, the number of electrons with:

• $l=1$ is $12$
• $l=2$ is $5$

So the correct option is: $\boxed{\text{B: }12\text{ and }5}$