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A radioactive substance has a half-life of four months. Three-fourth of the substance would decay in

Monjur Alahi

A radioactive substance has a half-life of four months. Three-fourth of the substance would decay in 

(a) 3 months (b) 4 months (c) 8 months (d) 12 months


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Salim Ahmed Kawsar

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(c) As it is given that half life of given substance is 4 months.

The amount of substance left after 4 months = 1/2 

The amount of substance left after 8 months = 1/4 

Therefore the amount of substance decay in 8

months = (1 – 1/4) = 3/4

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