Firstly, you should notice that for each 6moles of CO2 6moles of H2O is to be consumed in parallel for the reaction to occur. So it is 6:6 relation which means 1:1 relation. So whatever number of moles of CO2, the number of moles of H2O consumed should be exactly the same.
The equation to find the number of moles is:
#moles= mass used of the material/ molar mass of the material.
Now look closely, you only have both the used mass and the molar mass of CO2, and using the fact we mentioned before, so using the equation to find #moles of CO2 will give us a number that is exactly equal to the number of moles of H2O.
#moles of CO2= #moles of H2O= mass CO2/ molar mass CO2=
So #moles of H2O= 12mole.
Hope this helps.
The equation to find the number of moles is:
#moles= mass used of the material/ molar mass of the material.
Now look closely, you only have both the used mass and the molar mass of CO2, and using the fact we mentioned before, so using the equation to find #moles of CO2 will give us a number that is exactly equal to the number of moles of H2O.
#moles of CO2= #moles of H2O= mass CO2/ molar mass CO2=
So #moles of H2O= 12mole.
Hope this helps.