The reaction is $2H_2 + O_2 → 2H_2O$. 4g of H₂ reacts with 32g of O₂. Here, 8g of H₂ is mixed with 8g of O₂. Oxygen is the limiting reagent. 32g of O₂ produces 36g of water. Therefore, 8g of O₂ will produce (36/32) * 8 = 9g of water.