Question

Explain how hydrogen and helium nuclei were formed in the universe

Answer 1

Hydrogen and helium nuclei were formed in the universe through a process called nucleosynthesis. Deuterium (a hydrogen isotope) nuclei were formed when protons and neutrons combined. Neutrons combined with deuterium nuclei to form tritium. A proton would then fuse with tritium to form helium nuclei

Step-by-step explanation:

Answer 2

The nuclear reactions that formed 4He from neutrons and protons were radiative capture reactions. ... It took hundreds of thousands of years