When an element has Z=31 and 39 neutrons, what element and isotope is it?

A) ${}_{70}^{31}\mathrm{Ga}$
B) ${}_{70}^{31}\mathrm{Yb}$
C) ${}_{31}^{70}\mathrm{Ga}$
D) ${}_{31}^{70}\mathrm{Yb}$

Isotope

An isotope refers to one of two or more forms of an element with the same number of protons but a different number of neutrons in the nucleus, resulting in different atomic masses but similar chemical properties.

Element

A substance consisting of atoms which all have the same number of protons, fundamentally the simplest substances that cannot be broken down using chemical methods.