A Q from Bmat 2009

[Raph]

Hello!

2 g of a carbon compound is burnt in excess oxygen. 4.77g of CO2 is produced. What percentage (to the nearest 1%) of carbon is in the original compound?
A 21%
B 26%
C 42%
D 52%
E 65%

What is the meaning of the phrase “is in the original compound”? Is the meaning what is the percentage yield? what is the reaction equation? how to solve this ??

[winter1]

Hi, I think the original compound means the 2g of unknown carbon compound.

I’m not exactly sure with the balanced equation, but I got the percentage by
(CO2 moles)/(Unknown carbon compound moles) * 100%.

[Raph]

Thank you for answering! how did you get to 0.108 without a calculator?

[winter1]

I erased the process cause it looked messy but it looked something like this.
I rounded up to 3 significant points

(Actual integer)