The mass percent of carbon in carbon dioxide is : 

1. 0.034% 2. 27.27%
3. 3.4% 4. 28.7%
(2) HINT: The mass per cent is described as the grams of solute per grams of solution, multiplied by 100 to get the percentage.
Explanation : Molecular mass of CO2=1×12+2×16=44g
1 g molecule of CO2 contains 1g atoms of carbon
 44 g of CO2 contain C=12 g atoms of carbon
 % of C inCO2=1244×100=27.27%
Hence, the mass per cent of carbon in CO2 is 27.27%