A radioactive sample contains 1280 g of nuclide with a half-life of 8 hours. How much remains after 40 hours?
Answer and explanation
Correct answer: C. 40 g
- Step 1: The number of half-lives is .
- Step 2: Remaining g.
Answer
40 g.
Why not the others: 128 g: the mass is divided by . 80 g: it halves one time too few. 20 g: it halves one time too many.
Practise more Atoms and Light.
Free questions with an explanation for every one, and full timed EJU Japan mock tests.
More Atoms and Light questions
- A photon has frequency 7.5 Hz. Using J s, what is its energy?
- A photon has frequency 6 Hz. Using J s, what is its energy?
- A photon has frequency 10 Hz. Using J s, what is its energy?
- A radioactive sample contains 1600 g of nuclide with a half-life of 12 hours. How much remains after 36 hours?
- A radioactive sample contains 640 g of nuclide with a half-life of 5 hours. How much remains after 25 hours?
- The photoelectric effect shows that light behaves as