Which of the following statements is true regarding the hydrogen atom?

The number of radial nodes of $3s$ and $2p$ orbitals are respectively.

The orbital angular momentum of an electron in an $s$ orbital is:

If the electronic configuration of a nitrogen atom were $1s^7$,its energy would be lower than the ground state configuration $1s^2 2s^2 2p^3$ because the electrons would be closer to the nucleus. However,the configuration $1s^7$ is not observed. Which of the following principles is violated?

The number of nodal planes a $d$ orbital has is:

Which of the following statements are correct?
$(A)$ The electronic configuration of $Cr$ is $[Ar] 3d^5 4s^1$.
$(B)$ The magnetic quantum number may have a negative value.
$(C)$ In the ground state of an atom, the orbitals are filled in order of their increasing energies.
$(D)$ The total number of nodes is given by $n-1$.
Choose the most appropriate answer from the options given below.