Water consists of hydrogen and oxygen. The relative molecular mass of a water molecule is 18.

17 makes the result more accurate.

18.3 20 to 3 2 to 1

19.2 14 39 to 127 to 48 127/2 14 times 100% 20. 1 to 58.93 2 compound.

2 1.-N M-33N+ 16 22。 Carbon element 152-