Atoms And Nuclei Question 260

Question: If the mass number of an atom is $ A=40 $ and its electron configuration is $ 1s^{2},\ 2s^{2},\ 2p^{6},\ 3s^{2},\ 3p^{6} $ , the number of neutrons and protons in its nucleus will be [RPMT 2002]

Options:

A) 22, 18

B) 18, 22

C) 20, 20

D) 18, 18

Show Answer

Answer:

Correct Answer: A

Solution:

Number of protons = 2 + 2 + 6 + 2 + 6 = 18 Number of neutrons = 40 ? 18 = 22.



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