Which one of the following contains 38.7% carbon by mass?

Question

Quizplus · Accepted Answer

To find the percent by mass of carbon in a compound, we need to find the atomic mass of carbon and divide it by the total atomic mass of the compound, then multiply by 100. 
For compound A, there is no carbon present. 
For compound B, the atomic mass of carbon is 12 and the total atomic mass of the compound is 15, so the percent by mass of carbon is 80%. 
For compound C, the atomic mass of carbon is 12 and the total atomic mass of the compound is 29, so the percent by mass of carbon is approximately 41.4%. 
For compound D, the atomic mass of carbon is 12 and the total atomic mass of the compound is 44, so the percent by mass of carbon is approximately 27.3%. 
Therefore, the best choice containing 38.7% carbon by mass is C.

Which One of the Following Contains 38