90% of a radioactive sample is left undecayed | vedclass

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Question

Given that $90 \%$ is left un-decayed after time $t$.

Hence, $10 \%$ decays in time $t$

Initially assume that the amount of substance is $'x

Vedclass · Accepted Answer

$19$

Vedclass · Answer

Given that $90 \%$ is left un-decayed after time $t$.

Hence, $10 \%$ decays in time $t$

Initially assume that the amount of substance is $'x'$

After time $t^{\prime} 10 \%$ is decayed.

i.e. Amount of substance left $=0.9 x$

After further time $t^{\prime}$ another $10 \%$ is decayed.

i.e. $0.1 	imes 0.9 x$ is decayed

Leaving behind $0.81 x$.

Hence after time $2 t$ we see that $0.19 x$ has decayed, which is $19 \%$

$90\%$ of a radioactive sample is left undecayed after time $t$ has elapsed. What percentage of the initial sample will decay in a total time $2t$ : ..............$\%$

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