One of the biggest evidence that big bang produced hydrogen and helium is the Cosmic Background radiation proof. CBR is basically the matter and antimatter energy released during the Big Bang. The evidence of CBR are apparent as a radio signal which have a temperature of 2.7 K. Also, through extensive spectroscopic surveys from distant stars and galaxies , it is found that hydrogen and helium make up all the matter in the universe. Hydrogen accounts for 74% while helium contributes 25% of the total mass.
