A sample of a radioactive isotope has ¼ of its original activity after 36 days. What is the half life of this isotope?

No. of half-lives, n=

3

12

=4

Amount left after n half-lives A=

2

n

A

0

3g=

2

4

A

0

or 3g=

16

A

0

∴A

0

=48 g.

Explanation:

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it is easily magnetized.

33: i think it’s b