Half-Life

Uranium-232 has a half-life of 68.9 years. A sample from 206.7 years ago contains 1.40 g of uranium-232. How much uranium was originally present? 11.2 ✔ g

11.2 ✔ g

A sample contains 6.25 percent parent isotope and 93.75 percent daughter isotopes. If the half-life of the parent isotope is 58 years, how old is the sample? 232 ✔ years

232 ✔ years

An 80.0 g sample of iodine-131 was placed in a sealed vessel forty days ago. Only 2.5 g of this isotope is now left. What is its half-life? 8 ✔ days

8 ✔ days

Argon-39 has a half-life of 269 years. How long will it take for 52.5 g of a 60.0 g sample to decay to its daughter isotope? 807 ✔ years

807 ✔ years

Identify the daughter isotope in this nuclear reaction: Which is the daughter isotope? ✔ A) 218/86 Rn B) 4/2 He D) 222/88 Ra

✔ A) 218/86 Rn

Which time frame correctly describes the range of half-lives? ✔ A) fractions of a second to billions of years B) seconds to minutes C) minutes to days D) days to millions of years

✔ A) fractions of a second to billions of years

Rachel has an unknown sample of a radioisotope listed in the table. Using a special technique, she is able to measure the mass of just the unknown isotope as 104.8 kg at 12:02:00 P.M. At 4:11:00 P.M. on the same day, the mass of the unknown radioisotope is 13.1 kg. Which radioisotope is in the sample? A) Potassium-42 B) Nitrogen-13 ✔ C) Barium-139 D) Radon-220

✔ C) Barium-139

Identify the parent isotope and daughter isotope in this nuclear reaction: Which is the parent isotope? A) 212/86 Rn B) 4/2 He ✔ D) 222/88 Ra

✔ D) 222/88 Ra