What were the predominant elements composing the universe at its beginning?
Answer
Hydrogen and helium
The universe initially consisted predominantly of the simplest elements, hydrogen and helium, before stellar nucleosynthesis forged heavier elements.

Frequently Asked Questions
What were the predominant elements composing the universe at its beginning?What physical mechanism powers a star and keeps it from collapsing under its own gravity?What dictates the maximum extent to which a star can forge new elements?What process fuses three helium nuclei into carbon, often occurring in smaller stars like the Sun?What element accumulates in the inert core of a massive star just before a catastrophic collapse?Why does nuclear fusion, which releases energy for lighter elements, cease to be an energy source when iron is formed?What fundamental astrophysical process is required to synthesize elements heavier than iron?Which energetic events are considered the primary sites for the synthesis of the heaviest elements via the r-process?Where does the slow neutron-capture process (s-process) typically occur?How are elements forged within stars returned to the interstellar medium for future stellar generations?