## MCAT Question A Day - 10/17/14 - Answer!

**A natural sample of carbon contains 99% of**

^{12}C. How many moles of^{12}C are likely to be found in a 48.5 gram sample of carbon obtained from nature?

**A.**1

**B.**4

**C.**12

**D.**49.5

*B is correct. Don't do any complicated calculations. This is the type of problem that everyone will get right, but many will spend too much time trying to be exact. First assume that 100% of the sample is*

^{12}C. Now use the formula: moles = grams/molecular weight. This is very close to 4. The 1% that is not^{12}C is insignificant.

*Want more questions? - Click here to check out our MCAT Question A Day archive*