Question

Name an isotope of hydrogen which

i) has same number of protons and neutrons.

ii) is most abundant on earth.

Answer 1

1. Deuterium $\left({}_1{}^2\mathrm{H}\right)$,is the isotope of hydrogen which has same number of protons and neutrons.
2. Protium $\left({}_1{}^1\mathrm{H}\right)$, which is another isotope of hydrogen which is most abundant (99.8%) on earth.