# 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

Relevance

- Anonymous9 years ago
the mass number of an element ( A) = N (neutrons) + Z ( protons)

=> A = 20 + 19

=> A = 39

the answer is d

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