Which of these forms of carbon are used to determine carbon dating?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Carbon-14
Carbon dating finds the age of things that were once alive (wood, bone, cloth). Living beings take in carbon, including a fixed small share of the radioactive isotope carbon-14. After death no fresh carbon is taken in, and the carbon-14 decays with a half-life of about 5,730 years, so the carbon-14 left in a sample tells how long ago it died.
Why the other options are incorrect
Option (1) Carbon-12 — Incorrect. Carbon-12 is the stable isotope; it does not decay, so it serves only as the reference against which carbon-14 is compared.
Option (3) Coke Charcoal — Incorrect. Coke and charcoal are impure forms of carbon used as fuels, not isotopes.
Option (4) Graphite — Incorrect. Graphite is a crystalline form (allotrope) of carbon, used in pencils and electrodes.