Okay
Mr (H2O)= 18g
therefore moles of H2O
is 720.8/18= 40.04mol
the ratio of H2 to O2 to H2O is
2 : 1 : 2
so moles of H2 is same as H2O here
H2= 40.04moles
moles of O2 is half
so 40.04 x 0.5
20.02moles
grams of O2 is
its moles into Mr of O2
that's 20.02 x 32 = 640.64g
The answer is zero also I suggest googling the questions there is a quizlet with the answers

If every oxygen ion is combined with an aluminium ion has a charge of -2,the charge of each aluminum ion would be -3.
Uncharged Aluminum atom must need to lose it's electrons,in order to form the bond with oxygen which has vacant orbitals
ion
atom that has a positive or negative charge because it lost or gained one or more electrons
chemical bond
the attractive force that holds atoms or ions together
ionic bond
a chemical bond in which one atom loses an electron and the other atom gains electrons to form ions
chemical formula
a combination of chemical symbols and numbers to represent a substance
covalent bond
bond formed by the sharing of electrons between atoms
There are 2071.79 grams of glucose in 11.5 moles.
Answer:
The boiling point of sample X and sample Y are exactly the same.
Explanation:
The difference between sample X and sample Y is that they occupy different volumes. However, they both contain pure water. Remember that pure water has uniform composition irrespective of its volume.
Volume does not affect the boiling point as long as the volume is small enough not to give rise to significant pressure changes in the liquid.
The boiling point of a liquid is the temperature at which the pressure exerted by the surroundings upon a liquid is equaled by the pressure exerted by the vapour of the liquid; under this condition, addition of heat results in the transformation of the liquid into its vapour without raising the temperature.
It can be clearly seen from the above that the volume of a solution of pure water does not affect its boiling point hence sample X and sample Y will have the same boiling point.