Question

irrespective of the source , pure sample, of water always yields 88.89% mass of oxygen and 11.11% mass of hydrogen. this is explained bye the law of
a)conservation of mass
b)multiple proportions
c)constant compositions
d)constant volume

Answer 1

It will be explained by law of constant composition.
H₂O contains , 2 g of hydrogen and 16 g of oxygen .
Therefore , the hydrogen to oxygen ratio is = $\frac{2}{16}$ = 1:8 by mass
Now , percentage of oxygen in H₂O = $\frac{8}{1+8}\times 100$ = 88.89 %
Percentage of hydrogen in H₂O is = $\frac{1}{1+8}\times 100$ = 11.11 %
Hence , both the values are coming constant. Therefore , it will obey law of constant composition.