The number of unpaired electrons in $Ni$ (atomic number $= 28$) is:

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?

Which of the following statements is not correct?

In a multielectron atom,which of the following orbitals described by three quantum numbers will have the same energy in the absence of electric and magnetic fields?
$A: n=1, \ell=0, m_{\ell}=0$
$B: n=2, \ell=0, m_{\ell}=0$
$C: n=2, \ell=1, m_{\ell}=1$
$D: n=3, \ell=2, m_{\ell}=1$
$E: n=3, \ell=2, m_{\ell}=0$
Choose the correct answer from the options given below:

On the basis of quantum numbers,justify that the sixth period of the periodic table should have $32$ elements.

Which of the following sets represents degenerate orbitals?