Question 496: Atoms & Nuclei

Question

The half life of a radioactive substance is 30 minute. The time taken between 40% decay and 85% decay of the same radioactive substance is

Accepted Answer

When $$40 \%$$ nuclei decay, $$60 \%$$ nuclei remain undecayed
Let this number be $$\mathrm{N}_0$$
When $$85 \%$$ nuclei decay, $$15 \%$$ nuclei remain undecayed This number will be $$\mathrm{N}=\frac{\mathrm{N}_0}{4}$$
The number of nuclei will become one-fourth in two half lives i.e. 60 minutes.

Answer

15 minute

Answer

90 minute

Answer

60 minute

Answer

30 minute

Atoms & Nuclei

The half life of a radioactive substance is 30 minute. The time taken between 40% decay and 85% decay of the same radioactive substance is

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