Lana balanced an equation so that the result was 2C2H3Br + 5O2 → 4CO2 + 2H2O + 2HBr. Which most likely represents the starting equation?

Starting with C2H3Br + O2 → CO2 + H2O + HBr, balance carbon and bromine to get 2CO2 and 1HBr. The three hydrogen atoms then require 1H2O, giving 5 oxygen atoms on the right, or 5/2 O2 on the left. Multiply every coefficient by 2 to clear the fraction, producing the stated equation. So the starting equation is choice D, C2H3Br + O2 → CO2 + H2O + HBr.

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