Question

Please help with #9!

Answer 1

 M(O)= 16 g/mol
M(H)=1 g/mol

m(O)/m(substance)

1) 16/17
2)16/18
3) 16/19
4) 32/34=16/17

1) and 4) give the same answers, and 16/17 are the greatest fraction, so greatest % oxygen by mass also.

The answers should be 1) and 4).