How many moles of hydrogen are needed to produce 0.253 mol of water?

using the equation of formation of water:

H2+O2>H2O

Balancing the equation,

2H2+O2>2H2O

So now use the ratio from the balance equation, we know that 2 mol of H2 are producing 2 mol of H2O so the ratio will be 1:1.

So as 2 mol of H2O are produced by 2 mol of H2.

That implies 1 mol of H2O are produced by 1 mol of H2.

That is 0.253 mol of H2O are produced by 0.253 mol of H2.