Number of unpaired electrons in $Fe^{+3}$ $(Z = 26)$ is

From which principal quantum number $(n)$ do the $s, p, d,$ and $f$ orbitals start? Describe them.

The number of quantum numbers required to describe an electron in an atom completely is

The number of unpaired electrons in the excited state of carbon is equal to the number of unpaired electrons in which of the following?

In a multi-electron atom,which of the following orbitals described by the three quantum numbers will have the same energy in the absence of magnetic and electric fields?
$1. n = 1, l = 0, m = 0$
$2. n = 2, l = 0, m = 0$
$3. n = 2, l = 1, m = 1$
$4. n = 3, l = 2, m = 0$
$5. n = 3, l = 2, m = 0$

The total number of electrons in all orbitals having principal quantum number $n = 2$ and azimuthal quantum number $l = 1$ is ..........