The half-life of N is 6.5 s. A sample of this nuclide of hydrogen is observed for 32.5 s. The fraction of the original radioactive isotope remaining after this time is:
Correct answer: A. 1/32
- A. 1/32
- B. 1/16
- C. 1/8
- D. 1/4
Explanation
The explanation is given below: To find the fraction of the original radioactive isotope of nitrogen (N) remaining after 32.5 seconds, we can use the concept of radioactive decay and the half-life of the isotope. The half-life of N is 6.5 seconds, which means that in 6.5 seconds, half of the original sample will decay, and the other half will remain. For each successive half-life period, half of the remaining sample will decay, and the other half will persist. To calculate the fraction remaining after 32.5 seconds, we need to determine how many half-life periods have elapsed during this time. 32.5 seconds ÷ 6.5 seconds per half-life = 5 half-life periods. For each half-life period, the fraction remaining is halved, so after 5 half-life periods, the fraction remaining is (1/2)^5, which is equal to 1/32. So, after 32.5 seconds, 1/32 of the original radioactive isotope of nitrogen remains.
Last updated
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
1,254 free Nuclear Physics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Physics questions like this
Physics is on 13 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
87Ra221 is a radioactive substance having half-life of 4 days. Find the probability that a nucleus undergoes decay after two half-lives.
A 32g phosphorus is decayed and 2g remains undecayed after 60 days. The half-life of phosphorous is:
A 32g radioactive element decays and remains 2g after 60 days. What is the half- life of radioactive element?
A 32g radioactive elements decays and remains 2g after 60 days. What is half-life of this radioactive elements?
A certain radioactive isotope has a half-life of 50 days. Fraction of the material left behind after 100 days will be: