Answer:
5.60 Liters at STP
Step-by-step explanation:
First you need the balanced reaction equation
2 H2 + O2 ====> 2 H2O
4 g of oxygen ( O2 ) is 4/(15.999*2) moles of O2 (using periodic table)
Twice the number of moles of H2O re produced (from equation)
at STP the volume of a mole of gas is 22.4 liter/ mole
put all of this together
2 * 4 / (15.999*2) moles * 22.4 L/mole = 5.60 L