The number of unpaired electrons in the $p$-subshell of oxygen atom is

The quantum numbers of six electrons are given below. Arrange them in order of increasing energies. If any of these combination$(s)$ has/have the same energy,list them:
$(1).$ $n=4, l=2, m_l=-2, m_s=-1/2$
$(2).$ $n=3, l=2, m_l=1, m_s=+1/2$
$(3).$ $n=4, l=1, m_l=0, m_s=+1/2$
$(4).$ $n=3, l=2, m_l=-2, m_s=-1/2$
$(5).$ $n=3, l=1, m_l=-1, m_s=+1/2$
$(6).$ $n=4, l=1, m_l=0, m_s=+1/2$

The incorrect set of quantum numbers $(n, l, m, s)$ for an electron in $3p$ orbital is

For the energy level with the principal quantum number $n = 3,$ the number of possible orbitals is

The quantum number $m$ of a free gaseous atom is associated with

How is an electron in an atom identified? State the parameters used.