An atom has 7 electrons in its M- shell and contains 18 neutrons in its nucleus. What is its mass number ?





  • : 532
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  • Exam: Atomic Structure QUESTIONS

    Correct Answer to this question is 25 as the mass number is the sum of neutron and proton in the atom and in this case number of proton = number of electron that is 7 and number of neutrons are 18. Which means that the mass number of the atom is equal to 18+7=25.

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