If 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{

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13.Nuclei

medium

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

22, 18

18, 22

20, 20

18, 18

(a)Number of protons $= 2 + 2 + 6 + 2 + 6 = 18$
Number of neutrons $= 40 -18 = 22.$

Standard 12

Physics

hard

(JEE MAIN-2018)

medium

(AIPMT-1990)

easy

easy

easy