The quantity of uranium is 400g, the amount of uranium left after 3 half lives is:
Correct answer: B. 50g
- A. 25g
- B. 50g
- C. 100g
- D. 200g
Explanation
After every half life, the amount of uranium halves. Following this idea, after the first half life, the amount of uranium drops from 400g to 200g. After the second half of life, it drops to 100g. And finally after the third half life, what remains is 50 grams of uranium.
This question appeared on the UHS MDCAT 2017 paper, which you can sit online with every answer explained.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Half-life and Rate of Decay
Half-life is the time required for half the unstable nuclei in a sample to decay, and it remains constant for a particular radioactive nuclide. Questions use the exponential decay law, decay constant, activity, remaining quantity and mean life. Radioactive decay is random for individual nuclei but predictable for large samples.
Practise Nuclear Physics
1,257 free Nuclear Physics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 16 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Half-life and Rate of Decay questions
The relation between the decay constant 'λ' and the half-life T12 of a radioactive substance is:
A certain radioactive mass decays from 64 gm to 2 gm in 20 days. What is its half - life?
A 32g radioactive elements decays and remains 2g after 60 days. What is half-life of this radioactive elements?
The ratio between mean life and half-life is:
The half-life of a radioactive source is 2.3 days. Its decay constant per day will be:
The half-life of the given sample is 44 years. The sample will reduce to 50% of the original value after: