H

 A

The most abundant element in the universe is hydrogen.

Here are 3 key points:

1. Hydrogen dominates the universe

• Hydrogen makes up about ~75% of all normal (baryonic) matter by mass

• It is the simplest element: one proton + one electron

2. It formed first after the Big Bang

• Hydrogen was created in large quantities during Big Bang nucleosynthesis

• It became the building block for all later elements

3. It fuels stars and cosmic evolution

• Stars are mostly hydrogen and produce energy by fusing hydrogen into helium

• This process creates heavier elements and powers galaxies

Overall takeaway:
Hydrogen is the universe’s foundational element—it is the raw material from which stars, planets, and eventually complex elements are formed.