Most of the sun's mass is hydrogen. At high temperature and pressure inside the sun, some hydrogen is fused into helium. This nuclear reaction produces the sun's energy. But the reaction is not as simple as hydrogens combining into helium - in the sun, the process is catalyzed by intermediate reactions with carbon, nitrogen and oxygen in a process called the CNO cycle. For more detail, search "Stellar nucleosynthesis".
Most of the sun's mass is hydrogen. At high temperature and pressure inside the sun, some hydrogen is fused into helium. This nuclear reaction produces the sun's energy. But the reaction is not as simple as hydrogens combining into helium - in the sun, the process is catalyzed by intermediate reactions with carbon, nitrogen and oxygen in a process called the CNO cycle. For more detail, search "Stellar nucleosynthesis".
mistake :)