Question

2H2 + O2 --> 2H2O

Answer 1

12 moles of oxygen. Hope this works!

Answer 2

Answer: D. 12 moles

Explanation: $2H_2+O_2\rightarrow 2H_2O$

According to law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products must be same as the mass of reactants. The number of atoms of each element must be same on both sides of the equation. Thus a balanced chemical equation is written.

As can be seen from the chemical equation,

2 moles of hydrogen react with 1 mole of oxygen.

Thus 6 moles of hydrogen will react with=$\frac{1}{2}\times 6=12$ moles of oxygen.