What is the first element to form after the Big Bang?

What is the first element to form after the Big Bang?

• A. Helium
• B. Hydrogen
• C. Carbon
• D. Oxygen

Answer: (B)

Shortly after the Big Bang, the universe was hot and dense enough for protons and neutrons to form and then fuse into the lightest nuclei. The simplest, most stable nucleus is the hydrogen nucleus (a single proton), so hydrogen appears first as the basic building block of matter. Helium and other light elements form a bit later as conditions cool further and fusion proceeds, but they come after hydrogen in the sequence. Heavier elements like carbon and oxygen aren’t produced in meaningful amounts in the early universe; they’re built later inside stars through successive fusion reactions.