Question

An element $X$ with mass number $A$ and atomic number $Z$ is represented by

• A. $X$
• B. ${}_{A}X^Z$
• C. ${}_{Z}X^A$
• D. ${}_{Z}X^{A-Z}$

Answer 1

The correct option is C

${}_{Z}X^A$

Option (C)

1. The symbol of the element is $X$.
2. The atomic mass of an element is the sum of the total number of neutrons and protons in the atom. The atomic mass of the element is represented by $A$.
3. The atomic number is the total number of protons present in the nucleus of an atom. The atomic number of the element is represented by $Z$.
4. So, representation of the element is ${}_{Z}X^A$.

Hence, the correct answer is option (C).