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Question
Radioactive decay follows first-order kinetics. The initial amount of two radioactive elements X and Y is 1 gm each. What will be the ratio of X and Y after two days if their half-lives are 12 hours and 16 hours respectively?
Solution
For first-order reaction
half life of X = 12 hours
2 days = 48 hours means 4 half lives,
Amount of X left = `1/16` of initial value
half life of Y = 16 hours
2 days = 48 hours means 3 half lives,
Amount left = `1/8` of initial value
Ratio of X : Y = 1 : 2
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