If rate of reaction decay of a radioactive isotope decreases from 200 counts per minutes to 25 counts per minute after 24 hours. What is half life?
Correct answer: D. 8 hours
- A. 3 hours
- B. 6 hours
- C. 4 hours
- D. 8 hours
Explanation
Option D is correct.The half-life of a radioactive isotope is the time it takes for half of the radioactive atoms in a sample to decay. In your example, the half-life of the radioactive isotope is 8 hours. This means that after 8 hours, half of the radioactive atoms in the sample will have decayed. After 16 hours, half of the remaining radioactive atoms will have decayed, and so on. If the rate of reaction decay of a radioactive isotope decreases from 200 counts per minutes to 25 counts per minute after 24 hours, this means that the isotope has decayed for 3 half-lives. To calculate the number of half-lives, we can use the following equation: number of half-lives = time / half-life In this case, the time is 24 hours and the half-life is 8 hours. This gives us:number of half-lives = 24 hours / 8 hours = 3 half-lives Therefore, the rate of reaction decay of the radioactive isotope has decreased by a factor of 2^3 = 8. This is because each half-life, the number of radioactive atoms in the sample is halved.
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Reaction kinetics relates reaction rate to concentration, temperature, surface area and catalysts. Questions cover rate laws, reaction order, rate constants, activation energy and the activated complex, including how a catalyst lowers the activation energy without changing the overall energy change or equilibrium position.
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