1) The maximum number of electrons that can have principal quantum number, n = 3 and spin quantum number $m_{s}=-\frac{1}{2}$ , is A) 9 B) 5 C) 8 D) 7 Answer: Option AExplanation:when n = 3, l = 0, 1,2 i.e., there are 3s, 3p and 3d orbitals. If all these orbitals are completelyoccupied as Total 18 electrons ,9 electrons with s=+$\frac{1}{2}$ and 9 with a= $-\frac{1}{2}$
