Respuesta :

beeaans
To start, you need to find how many grams are in one mole of water. 
H2= 2.00g
O= 16.00g
So we know that one mole of water is 18 grams. The last step is to just divide 1.287g by 16 grams to get an answer of .0804375 moles of water. Hope this helps!