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

What is the atomic number of the element with $M^{2+}$ ion having electronic configuration $[Ar] 3d^8$?

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?
$1. n = 1, l = 0, m = 0$
$2. n = 2, l = 0, m = 0$
$3. n = 2, l = 1, m = 1$
$4. n = 3, l = 2, m = 0$
$5. n = 3, l = 2, m = 0$

Which of the following electronic configurations has the least energy?

The two electrons in the $K$ shell will differ in which of the following quantum numbers?

The number of angular nodes and radial nodes in $3s$ orbital are