The representation of the ground state electronic configuration of $He$ by box-diagram as $\uparrow \uparrow$ is wrong because it violates

Which of the following sets of quantum numbers is allowed?

Which of the following is/are not correct with respect to energy of atomic orbitals of hydrogen atom?
$A$. $1s < 2p < 3d < 4s$
$B$. $1s < 2s = 2p < 3s = 3p$
$C$. $1s < 2s < 2p < 3s < 3p$
$D$. $1s < 2s < 4s < 3d$
Choose the correct answer from the options given below:

Consider the following statements:
$(A)$ The principal quantum number $'n'$ is a positive integer with values of $'n'=1, 2, 3, \dots$.
$(B)$ The azimuthal quantum number $'l'$ for a given $'n'$ (principal quantum number) can have values as $'l'=0, 1, 2, \dots, (n-1)$.
$(C)$ Magnetic orbital quantum number $'m_l'$ for a particular $'l'$ (azimuthal quantum number) has $(2l+1)$ values.
$(D)$ $\pm 1/2$ are the two possible orientations of electron spin.
$(E)$ For $l=5$,there will be a total of $11$ orbitals.
Which of the above statements are correct?

When the principal quantum number is $n = 3$,the possible values of the azimuthal quantum number $(l)$ are:

The correct set of four quantum numbers for the valence electron of strontium $(Z=38)$ is: