Which chemical equation below shows a balanced reaction that follows the law of conservation of mass?

Question

a: H2 + O2 = H2O
b: 2H2 + O2 = 2H2O
c: H2 + O2 = 2H2O
d: 2H2 + 2O2 = 2H2O

Answer 1

b: 2H2 + O2 = 2H2O