What Mass Of Hydrogen Peroxide (H2O2) Must Decompose To Produce 0.77 G Of Water?

Hydrogen has an atomic mass of 1g and oxygen has an atomic mass of 16g
 
Molecular Mass of H2O2:
2 x 1 + 2 x 16 = 34g.
 
Decomposition of H2O2:
2 H2O2 --> 2 H2O + O2
or in other words,
2 x 34g --> 2 x 18g + 32g
68g = 36g + 32g
 
68g x 0.77g / 36g = 1.4544g H2O2