The rate at which a radioactive element decays is its ____.
quarter life
whole life
wonderful life
half life
2. Multiple Choice
1 minute
1 pt
what's the half life of this substance?
1 day
2 days
3 days
4 days
3. Multiple Choice
15 minutes
1 pt
The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed?
100.0g
50.0g
12.5g
8.5g
4. Multiple Choice
15 minutes
1 pt
Barium-122 has a half-life of 2 minutes. A fresh sample weighing 80 g was obtained. If it takes 10 minutes to set up an experiment using barium-122, how much barium-122 will be left when the experiment begins?
0.25g
2.5g
25g
80g
5. Multiple Choice
1 minute
1 pt
The half-life of strontium-90 is 25 years. How much strontium-90 will remain after 100 years if the initial amount is 4.0 g?
3.0g
0.25mg
0.3g
0.25g
6. Multiple Choice
30 seconds
1 pt
If the half life of a radioactive element is 100yrs, how long would it take for the radioactivity to reduce by one half?
200yrs
100yrs
50yrs
300yrs
7. Multiple Choice
30 seconds
1 pt
What is a half-life?
The average time it takes for any element to disappear completely
The time it takes for a radioactive atom to lose half its neutrons
The time it takes for half of any number of radioactive atoms to decay
The time it takes for a radioactive atom to lose half its electrons
8. Multiple Choice
1 minute
1 pt
Imagine you have 50,000 atoms of uranium-238. If U-238 has a half-life of 4.5 billion years, how many U-238 atoms will be left after 4.5 billion years?
25,000
50,000
12,500
0
9. Multiple Choice
1 minute
1 pt
If 10 mg of iodine 131 is given to a patient, how much is left after 24 days? The half-life of iodine-131 is 8 days.
1.25mg
1.25g
10g
10mg
10. Multiple Choice
1 minute
1 pt
If the half-life of uranium-232 is 70 years, how many half-lives will it take for 10 g of it to be reduced to 1.25 g?
1 half-life
2 half-lives
3 half-lives
4 half-lives
11. Multiple Choice
15 minutes
1 pt
The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed?
100.0g
50.0g
12.5g
8.5g
12. Multiple Choice
30 seconds
1 pt
The half-life of strontium-90 is 25 years. How much strontium-90 will remain after 100 years if the initial amount is 4.0 g?
3.0g
0.25mg
0.3g
0.25g
13. Multiple Choice
15 minutes
1 pt
If the half-life of uranium-232 is 70 years, how many half-lives will it take for 10 g of it to be reduced to 1.25 g?
1 half-life
2 half-lives
3 half-lives
4 half-lives
14. Multiple Choice
1 minute
1 pt
What is the half-life of iodine-131?
32 days
8 days
16 days
24 days
15. Multiple Choice
45 seconds
1 pt
The half life of an element is 20 minutes. What % of the element remains after an hour?