Q145 / 160 · AP EAMCET 2020 (07 Oct Special) · Physics

The half-life of a radioactive sample is 20 days this means that

A
the substance completely disintegrates in 40 days
B
the substance completely disintegrates in 80 days
C
$1 / 8$ part of the substance disintegrates in 60 days
Correct answer
D
$7 / 8$ part of the substance disintegrates in 60 days

Hence, the correct answer is option: 'D'.

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