What element has a mass number of 40 and 20 protons?

1 Answer
Sep 15, 2016

Answer:

#""^40Ca#.

Explanation:

If there are 20 protons, then #Z=20#, and thus the element is calcium. There are a further 20 neutrons in the nucleus, but this just determines the isotope. The #""^40Ca# isotope has approx. 97% natural abundance.