question_answer

The half-life of a radioisotope is four hours. If the initial mass of the isotope was 200 g, the mass remaining after 24 h undecayed is

A) 1.042g  

B)                        2.084 g 

C)        3.125 g          

D)        4.167 g

Correct Answer: C

Solution :

Ifnumber of half-lives,             amount left after y half-life initial amount