Radioactive Potassium-40 decays into Argon-40 at a known rate. This is shown in the diagram on the right.

Potassium-Argon dating was used to date a rock that a particular fossil was discovered in.The rock contained 25% of Potassium-40.

a. What would be the most accurate estimation of the age of this fossil? The Naracoorte Caves in South Australia is the site of the Victoria Fossil Cave. This massive chamber acted as a pitfall trap for millions of years, and tens of thousands of fossils have been discovered at this site. One such fossil, from the Jurassic period is pictured here.

b. What would be the appropriate conditions required for the formation of fossils such as this?

c. Occasionally, complete remains of organisms may be preserved. Discuss one way how an organism may be completely preserved.

d. What method of absolute dating would have been used to determine the age of this fossil -carbon 14 dating or Potassium-Argon dating? Justify you answer.