The half-life of a radioactive substance is 5 minutes. The amount of substance decayed in 20 min will be:
Correct answer: A. 93.75 %
- A. 93.75 %
- B. 6.25 %
- C. 25 %
- D. 75 %
Explanation
Half life T= 5 minGiven time t=20 minNumber of half lives n = giventime/half life n= t/T n= 20/5 n= 4Formula to find the number of atoms decayed is; N = 1-1/2n N = 1-1/24 N = 1-1/16 N = 15/16 Perecntage of number of atoms decayed= 15/16 *100% N= 93.75%
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