Question

if 100 gram of water is deccomposed how manygram of oxygen and hydrogen are obtain

Answer 1

there are 3 atoms in water, one of oxygen and 2 of hydrogen. And you can determine the mass of oxygen in water

Which is 16amu while the mass of hydrogen is 1 amu (2 hydrogen means 2 amu mass)

We know total mass of water is 18 amu  so the oxygen percentage in water will be = (16/18)*100= 88.9% approxiamately 89%

The remaining 11 % will be hydrogen

So in 100 g of water 89 g will be of oxygen while 11 g will be of hydrogen