What is the mass percent of carbon in oxalic acid, H2C2O4? Chemistry Chapter 6 What is the mass percent of carbon in oxalic acid, H2C2O4? A) 2.24 B) 13.3 C) 26.7 D) 34.5 E) none of the above Answer: C Learn More : Share this Share on FacebookTweet on TwitterPlus on Google+