Which of the following sets of quantum numbers is impossible for an electron?

Total number of angular nodes of orbitals associated with third shell $(n=3)$ of an atom is

The electronic configuration of calcium ion $(Ca^{2+})$ is

Among the elements from atomic number $1$ to $36$,the number of elements which have an unpaired electron in their $s$-subshell is

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

How many electrons in an atom can have the quantum numbers $n = 3, l = 2, m = +2, s = +1/2$?