Question

Which of the following orbitals described by three quantum numbers will have different energies for a multielectron atom, in the absence of external electric and magnetic fields?
$\text{(1) n = 1, l = 0, m = 0}$
$\text{(2) n = 2, l = 1, m = -1}$
$\text{(3) n = 2, l = 1, m = +1}$
$\text{(4) n = 3, l = 2, m = +1}$
$\text{(5) n = 3, l = 2, m = 0}$

• A. $\text{4 and 5}$
• B. $\text{1 and 2}$
• C. $\text{2 and 3}$
• D. $\text{None of these}$

Answer 1

The correct option is B $\text{1 and 2}$

According to Aufbau principle: Energy of the orbitals depend on $n+l$ value. Greater the value of $n+l$, greater will be the energy. 1 and 2 have different $n+l$ value. Hence, they will have different energies.