In the explosion of a hydrogen-filled balloon, 0.68 g of hydrogen reacted with 4.8 g of oxygen to form how many grams of water vapor? (Water vapor is the only product.)

I don't have the textbook for my class yet so I've been using various online resources to try and work this problem out and I've gotten 12.2g, 6.1g, 2.7g, and 5.4g. None of these answers were correct and I can no long receive credit on my online hw at this point for the question, but I'd really like to know what the correct way to work this problem out is. I feel really stupid.

Question

In the explosion of a hydrogen-filled balloon, 0.68 g of hydrogen reacted with 4.8 g of oxygen to form how many grams of water vapor? (Water vapor is the only product.)

I don't have the textbook for my class yet so I've been using various online resources to try and work this problem out and I've gotten 12.2g, 6.1g, 2.7g, and 5.4g. None of these answers were correct and I can no long receive credit on my online hw at this point for the question, but I'd really like to know what the correct way to work this problem out is. I feel really stupid.