this is so ez,
ok so here what u'll do after u balance the equation:
1. convert grams of oxygen to moles of oxygen.
2. convert moles of oxygen to moles of water
3. convert moles of water to grams of water.
4. bOOm... that's your answer
as follows:
2H2O(l)===>2H2(g)+O2(g)
1. 151200(g)/16(g/mol)=9540 moles of O2
2. 9450 moles of O2 × 2 moles of H2O =18900 moles of H2O
3. 18900 moles of H2O × 10g/mol = 189000g of H2O is required.