Question

An element Y is made up of 15 electrons and 16 neutrons. Which of the following is the correct symbolic representation of the element?

• A. ${}_{15}^{31}Y$
• B. ${}_{15}^{16}Y$
• C. ${}_{31}^{15}Y$
• D. ${}_{16}^{15}Y$

Answer 1

The correct option is A ${}_{15}^{31}Y$

$\bullet$ An element X is symbolically represented as ${}_Z^{A}X$, where 'Z' represents the atomic number and 'A' represents the mass number.

$\bullet$ Atomic number = number of protons = number of electrons

$\bullet$ Mass number = number of protons + number of neutrons

$\bullet$ For the given element, atomic number is 15 and mass number is 31. Hence, it is represented as: ${}_{15}^{31}Y$.