How many grams of water are made from the reaction of 16.0 grams of oxygen gas?

Assuming hydrogen gas is in excess, calculate the moles of oxygen 

n(O2) = 16.0 g / 32.0 g/mol = 0.500 mol 

Calculate the moles of water using the mole ratio; the ratio of H2O to O2 is 2:1 or the moles of H2O is twice the moles of O2 

n(H2O) = 2 x n(O2) = (2)(0.500) = 1.00 mol 

Calculate the mass of H2O by multiplying the moles by the molar mass of water 

mass = (1.00 mol)(18.0 g/mol) = 18.0 g H2O 

Ans: A)

The answer is b i think

All the elements are arranged by melting points on the periodic table. in row they go from metals to gasses. in the row from sodium to argon, sodium is more reactive than the one on its right, magnesium.