Question

The half-life of a certain radioactive
element is such that 7/8 of a given-
quantity decay in 12days. What fraction
remains undecayed after 24 days?
a) 0
b)1/128
c)1/64
d)1/32​

Answer 1

Hello Dear,

◆ Answer -

(c) 1/64

◆ Explaination -

Let A be initial mass of the element.

In 12 days, 7/8th of A is decayed. Remaining substance will be -

A' = A - 7A/8

A' = A/8

In next 12 days, 7/8th part of A' will decay. Remaining substance will be -

A" = A' - 7A'/8

A" = A/8 - 7/8 × A/8

A" = A/8 - 7A/64

A" = A/64

Therefore after 24 days, 1/64 th part of element is remaining.

Thanks dear...

Answer 2

Explanation:

Option C is the correct answer

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