What is the mass number of an element that has 19 protons, 19 electrons, and 20 neutrons?

a. 19

b. 58

c. 20

d. 39

3 Answers

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  • Best Answer

    39 = 19 protons + 20 neutrons.

  • Anonymous
    9 years ago

    the mass number of an element ( A) = N (neutrons) + Z ( protons)

    => A = 20 + 19

    => A = 39

    the answer is d

  • 9 years ago

    39...

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