question_answer

A radioactive isotope having a half life of 3 days was received after 12 days. It was found that there were 3 g of the isotope in the container. The initial weight of the isotope when packed was:

A)  36 g                                      

B)  48 g

C)  12 g                                      

D)  24 g

Correct Answer: B

Solution :

Half life of a radioactive isotope, \[{{t}_{1/2}}=3\]days Therefore, 12 days \[=4\times {{t}_{1/2}}\]\[\xrightarrow{{{t}_{1/2}}}48\,gm\] Initial wt. 1 day 2nd day 3rd day 4th day.