JEE Main & Advanced
Physics
Nuclear Physics And Radioactivity
Question Bank
Nucleus, Nuclear Reaction
question_answer
If the mass number of an atom is \[A=40\] and its electron configuration is \[1{{s}^{2}},\ 2{{s}^{2}},\ 2{{p}^{6}},\ 3{{s}^{2}},\ 3{{p}^{6}}\], the number of neutrons and protons in its nucleus will be [RPMT 2002]
A) 22, 18
B) 18, 22
C) 20, 20
D) 18, 18
Correct Answer:
A
Solution :
Number of protons = 2 + 2 + 6 + 2 + 6 = 18 Number of neutrons = 40 ? 18 = 22.