What is the origin of hydrogen, the smallest element?

• A. The Big Bang
• B. The Earth's core
• C. The Sun's fusion
• D. A primordial gas cloud

Answer: (A)

Hydrogen formed in the very early universe during Big Bang nucleosynthesis. In the first minutes after the Big Bang, the extreme heat and density allowed protons and neutrons to fuse into light nuclei, with the simplest nucleus—a single proton that becomes hydrogen—produced in vast amounts. As the universe cooled, electrons joined these nuclei to form neutral hydrogen atoms, making hydrogen the most abundant element today. The Sun’s fusion later uses hydrogen as fuel and converts it into helium, rather than creating hydrogen. The Earth's core formed from heavier planetary materials long after the Sun and planets formed. A primordial gas cloud describes the material present, not its origin. So the Big Bang is where hydrogen comes from.