What percentage of normal matter is composed of Hydrogen?

The correct answer is that approximately 90% of normal matter in the universe is composed of hydrogen. This is due to hydrogen being the simplest and most abundant element, making up about three-quarters of the universe's elemental mass. In many theoretical models of the cosmos and studies of the chemical composition of stars, galaxies, and interstellar gas, hydrogen consistently accounts for a significant majority of normal matter.

When considering the abundance of elements, hydrogen’s prevalence is primarily attributed to its formation during the earliest moments after the Big Bang and its role in the process of star formation. The high percentage illustrates hydrogen's fundamental importance in the universe's structure and evolution. Other elements are present in relatively smaller quantities compared to hydrogen, further emphasizing its dominance in the composition of normal matter.