Question

The number of neutrons present in the element ${}_Z^A\text{X}$ is given by ________.

• A. $\text{A-Z}$
• B. $\text{Z}$
• C. $\text{Z + A}$
• D. $\text{Z - A}$

Answer 1

The correct option is A $\text{A-Z}$

Symbolic representation of an element is given as ${}_Z^A\text{X}$.
Z is the atomic number
A is the mass number
X is the any given element.

Z = number of protons = number of electrons

A = number of protons + number of neutrons.
Hence, number of neutrons = $\text{A-Z}$