Question

The number of neutrons in an atom $X$ of atomic number $Z$ and mass number $A$ is

• A. zero
• B. $Z$
• C. $A-Z$
• D. $A$

Answer 1

Answer: (C)

$A-Z$

No of neutrons are given by: $(A-Z)$

Given an atomic number $\left(Z\right)$ and mass number $\left(A\right)$, you can find the number of protons, neutrons, and electrons in a neutral atom. For example, a lithium atom $(Z=3,A=7amu)$ contains three protons (found from $Z$), three electrons (as the number of protons is equal to the number of electrons in an atom), and four neutrons $(7–3=4)$.