The number of moles of hydrogen that is needed to produce 0.253 mol of water

The balanced equation that describes the reaction between hydrogen and oxygen to produce water is 2 H2+O2= 2H2O. Hence to produce 2 moles of water 2 moles of hydrogen is equivalently needed. For the given, 0.253 moles water thus needs 0.253 moles of hydrogen, too.

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