The mass number of the given element is 39.
The mass number can be described as the sum of the number of protons and neutrons in an atom. The mass number has also been known as the nucleon number. The mass number can be equivalent to the atomic mass of the element.
Mass number = Number of neutrons + Number of protons
Given, protons = 19
Neutrons = 20
Mass number = 19 + 20
Mass number = 39
The mass number of the given element is 39.
For more information about the mass number, refer to the link:
https://brainly.com/question/18803094
