Free Half-life and Rate of Decay MCQs with Answers
54 Half-life and Rate of Decay MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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.
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54 questions · page 3 of 3
- A. 125%
- B. 25%
- C. 50%
- D. 100%
Explanation: 50 days is one half life. So 100 days means 2 half lives.After every half life, the substance halves in amount.After the first half life…
Correct answer: 25%42. A 32g phosphorus is decayed and 2g remains undecayed after 60 days. The half-life of phosphorous is:
- A. 5 days
- B. 6 days
- C. 10 days
- D. 15 days
Explanation: 1 half life = 16g 2 half life = 8g 3 half life = 4g 4 half life = 2g 60/4=15 days
Correct answer: 15 days- A. 2 days
- B. 6 days
- C. 10 days
- D. 15 days
Explanation: The time taken for half of the original population of radioactive atoms to decay is called the half-life.
Correct answer: 15 days- A. Average life
- B. Mean life
- C. Total life
- D. Half-life
Explanation: Radioactive materials consist of unstable atoms that decay over time, emitting radiation in the process.
Correct answer: Half-life- A. 2 days
- B. 6 days
- C. 10 days
- D. 15 days
Explanation: The half-life of a radioactive element is the time it takes for half of the initial quantity to decay.
Correct answer: 15 days- A. 5 days
- B. 4 days
- C. 10 days
- D. 6 days
Explanation: Radioactive decay is an exponential decay process. Half life measures the time it takes for a given amount of the substance to become…
Correct answer: 4 days47. The relation between the decay constant 'λ' and the half-life T12 of a radioactive substance is:
- A. λ = 1/T1/2
- B. λ = 0693 T1/2
- C. λ = T1/2
- D. λ = 0.693/T1/2
Explanation: The time required for half of the original population of radioactive atoms to decay is called the half-life.
Correct answer: λ = 0.693/T1/2- 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…
Correct answer: 50g- A. Log2
- B. 1/log λ
- C. 1/λ
- D. (Log2)-1
Explanation: We have to remember formulaMean life = 1/lambda Half life = log2 / lambda =log2 × 1/lambdaReplacing 1/lambda by mean life,Half life = log2…
Correct answer: (Log2)-1- A. 0.1
- B. 0.2
- C. 0.3
- D. 2.3
Explanation: T1/2 = 0.693/λ.Where T1/2= half life and λ= decay constant When half life= 2.3 daysSo λ = 0.693/T1/2= 0.693/2.3=0.30 per day
Correct answer: 0.3- A. 22 years
- B. 88 years
- C. 11 years
- D. 44 years
Explanation: The correct answer is 44 years because the half-life of a sample is defined as the time required for half of the sample to decay.
Correct answer: 44 years- A. N0/8
- B. 2N0/3
- C. N0/3
- D. 7N0/8
Explanation: Each half-life reduces the remaining number of nuclei by half. After one half-life, N0/2 nuclei remain.
Correct answer: 7N0/8- A. X/32
- B. X/13
- C. X/8
- D. X/5
Explanation: Half life is 2.6 yearsInitially x grams of sodium isotope were present After 13 years which is 13/2.6 = 5 years Let the amount of sodium…
Correct answer: X/32- A. 12 hours
- B. 6 hours
- C. 2 hours
- D. 3 hours
Explanation: Original amount = 16gDecayed amount = 12gradioactive isotope left after 6 hours is, 16 g - 12 g = 4 gUse N = No/2nWhere N = 4g , No =…
Correct answer: 3 hours