What is the designation of an orbital with quantum numbers $n=4$ and $l=3$?

How many electrons can be accommodated in a sub-shell for which $n = 3, l = 1$?

An ion with a charge of $-2$ has the electronic configuration $1s^2, 2s^2, 2p^6$. Identify the ion.

Which of the following sets of quantum numbers is not valid?

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:
$(1)$ $n = 4, l = 2, m_l = 2, m_s = -1/2$
$(2)$ $n = 3, l = 2, m_l = 1, m_s = +1/2$
$(3)$ $n = 4, l = 1, m_l = 0, m_s = +1/2$
$(4)$ $n = 3, l = 2, m_l = -2, m_s = -1/2$
$(5)$ $n = 3, l = 1, m_l = -1, m_s = +1/2$
$(6)$ $n = 4, l = 1, m_l = 0, m_s = +1/2$

The number of atomic orbitals from the following having $5$ radial nodes is $.......$. $7s, 7p, 6s, 8p, 8d$