Question

Which radioisotope is used in dating geological

formations?
(1) I-131
(2) U-238
(3) Ca-37
(4) Fr-220

Answer 1

U- 238

Step-by-step explanation:

Uranium-238 is used to date many geological samples, especially on materials that are thousands to over a million years old

Answer 2

(2) U-238 is the radioisotope used in dating geological formations. Uranium-238 has a half-life of 4.46 billion years, which makes it suitable to date such old formations.
The other options do not have such long durabilities and half-lives.