Question

The half-life period of a radioactive substance is 5 min. The amount decayed in 20 min will be

Options

• 93.75%

• 75%

• 25%

• 6.25%

Answer 1

93.75%

Explanation:

`N/(No) = (1/2)^(1/T) = (1/2)^(20/5) = 1/16`

Amount decayed = `(16 - 1)/16 xx 100` = 93.75%.