which isotope of hydrogen is found in the nucleus of the sun?

Answer 1

Atomically, Sun is composed of about 90% 1H Hydrogen Thus giving us the Helium moecule when the fusion occurs. Had it been other isotopes, we would see most of the Helium isotopes but we dont. Its predominantly Helium-2.

Answer 2

According to the paper referencer, it should be the common hydrogen 1H but you can not speak of atoms in the sun, since the temperature is too high to have atoms The sun is rather a mixture of protons and electrons