UPSEE 2017 Solved Paper

The value of initial sample is 8000 . It decays in 4 days to half of the initial value i.e. 4000 atoms. In next four days, it further days to 2000 atoms. In next four days, it will again decay to 1000 atom i.e. half of the present initial value.
Hence,
8000

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4 days

4000

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4 days

2000

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4 days

1000
So, half life of sample (T1∕2)=4 days