Question

find the ratio by mass of the combining elements in the compound-c2h5oh

Answer 1

Total mass of compound $C_{2}H_{5}OH_$ (assuming one mole)
                                      = (2*12)+(1*5)+16+1
                                      = 24+5+16+1
                                      = 46 g 

Now, required ratio = Mass of Carbon : Mass of Hydrogen : Mass Of Oxygen
                               = 24 : 6 : 16

Simplifying the ratio, we get:

The ratio of the combining elements by mass in the compound $C_{2}H_{5}OH$ = 12 : 3 : 8.