A sample of a radioactive element with an initial mass of 24 g decays to 3 g in 36 minutes. How much of the original sample remained after the first 12 minutes?
Correct answer: A. 12g
- A. 12g
- B. 6g
- C. 2g
- D. 8g
Explanation
The initial mass which was 24 g reduced to 3 g, which is ⅛ of the total mass. So if the mass is reduced to ⅛ in 36 minutes, it must reduce to ½ of its value in 12 minutes. Hence Option A is correct.orInitial mass=24gFinal mass(in 36 minutes)=3gHere, we can see that in 36 minutes, the mass is reduced to 1/8th times the original. 24g----> 12g ---->6g ---->3g 12 mins 12 mins 12 minsThis decomposition requires 36 mins.Here, we can calculate that the half-life of the substance will be 12 mins as after every 12 mins the substance is the remaining half of the original. Here after 12 mins, 12g of the sample is left.
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