If the half-life of carbon-14 is 5700 years, and some plant remains from an archeological dig site have 1/8 the carbon-14 found in the atmosphere, what is the approximate age of the remains in the dig site in years?
- 700
- 5700
- 17000
- 45000
Click for Explanation
The half-life is the time it takes for 1/2 of a radioactive substance to decay. For example, 20 units of a substance with a half-life of 5 years will have 10 units remaining after 5 years. In this example, carbon-14 has undergone 3 half-lives: 1 → ½; ½ → ¼; ¼ → 1/8.
3 x 5700 years = 17100 years.
- 700, incorrect, This answer results from multiplying the amount of sample by the half life, 5700/8.
- 5700, incorrect, This is the half-life, not the amount of time elapsed during three half-lives.
- 17000, correct.
- 45000, incorrect, This answer results from multiplying the half-life by the remaining fraction: 5700 x 8.
Want more MCAT practice?
We’ve got options for every schedule and learning style!
From the best online MCAT course created by top instructors with 524+ MCAT scores to the most representative full-length practice exams and private tutoring, we can custom tailor your MCAT prep to your goals!
Not sure which option is right for you? Schedule a free MCAT consultation with an MCAT expert using the form below. No obligation, just expert advice.
Related Post
Search the Blog
Free Consultation
Interested in our Online MCAT Course, One-on-One MCAT Tutoring or Med admissions packages? Set up a free consultation with one of our experienced Senior Student Advisors.
Schedule NowPopular Posts
-
-
-
-
-
MCAT Blog How to Review MCAT Full-Lengths
Free MCAT Practice Account
Need great MCAT practice?Get the most representative MCAT practice possible when you sign up for our free MCAT Account, which includes a half-length diagnostic exam and one of our full-length MCAT practice exams.
Learn More
Submit a Comment