Answer:
Is the mass number
Explanation:
Every atom is usually identified by using two different numbers:
- Atomic number: generally labelled with Z, corresponds to the number of protons in the nucleus, so Z = p
- Mass number: generally labelled with A, corresponds to the number of protons+neutrons in the nucleus, so A = p + n
To find the number of neutrons in a nucleus, therefore, we can do
n = A - Z
