ECONOMICS
COMPOUND INTEREST
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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100.0g
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50.0g
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12.5g
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8.5g
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Detailed explanation-1: -Answer. Number of half-lives n = 7.2/2.4 = 3 Thus, three half-lives have passed. Amount remaining (N) =? N = N = 100 / 23 N = 100 / 8 N = 12.5 g As a result, the amount of Zn-71 remaining after 7.2 minutes is 12.5 g.
Detailed explanation-2: -The half-life of Zn-71 is 2.4 minutes.
Detailed explanation-3: -Therefore, after 32 years 6.25 g will remain.
Detailed explanation-4: -The amount of the radioactive substance that will remain after 3-half-lives=(½)3 × a, where a = initial concentration of the radioactive element. So, amount of the radioactive substance that remains aftet 3-half-lives=( ½)³x10 = 10/8= 1.25 g.
Detailed explanation-5: -Determine the original amount of the substance. Determine the amount of time for which the substance was measured. Determine the remaining amount of the substance after the time. Substitute these values into the half-life equation and solve for half-life.