Question

Which one of the following set of quantum numbers is not possible for electron in the ground state of an atom with atomic number 19?

• A. $ n=2,\,l=0,\,m=0 $
• B. $ n=2,\,l=1,\,m=0 $
• C. $ n=3,\,l=1,\,m=-1 $
• D. $ n=3,\,l=2,\,m=+\,2 $

Answer 1

Answer: (D)

$ K(Z=19):1\,{{s}^{2}},\,2{{s}^{2}}2{{p}^{6}},3{{s}^{2}}3{{p}^{6}},4{{s}^{1}} $ In the ground state, the value of $ l $ can be either zero or one. Hence, the set of quantum numbers i.e., $ \left( n=3,\text{ }l=2,\text{ }m=+2 \right) $ cannot be possible in the ground state of the atom.