2H2 + O2 - -> 2H2O

How many grams of oxygen gas are required to produce 90. g of water?

80g

Explanation:

2H2 + O2 - > 2H2O

MM of H2O = (2x1) + 16 = 2 + 16 = 18g/mol

Mass conc. of H2O from the balanced equation = 2 x 18 = 36g

MM of O2 = 16 x 2 = 32g/mol

From the equation,

32g of O2 reacted to produce 36g of H2O.

Therefore Xg of O2 will react to produce 90g of H2O i. e

Xg of O2 = (32x90) / 36 = 80g