Suppose a radioactive substance disintegrates completely in 10 days. Each day it disintegrates at a rate twice the previous day, Then, after nine days, the percentage left to be disintegrated is

(a) 10

(b) 25

(c) 20

(d) 50

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1 Answers

The correct option is (d) 50.

Explanation:

If it disintegrates completely in ten days, alter nine days, only half of the substance should remain. Then, on the tenth day, only the entire substance will disintegrate (i.e., 100%) because rate of disintegration on the tenth day will be double that of the 9th day, i.e., double of 50%.

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