The number of possible spatial orientations of an electron in an atom is given by its

Which of the following sets of quantum numbers represent an impossible arrangement?
$n$ $l$ $m$ $m_s$

The valence electrons in the carbon atom are

The electronic configuration of chromium ($Cr$,$Z=24$) is:

What is the total number of orbitals present in $N$ shell?

The correct decreasing order of energy for the orbitals having the following set of quantum numbers:
$A$. $n=3, \ell=0, m=0$
$B$. $n=4, \ell=0, m=0$
$C$. $n=3, \ell=1, m=0$
$D$. $n=3, \ell=2, m=1$