Question

The half-life period of radium is 1620 years. In how much time 1 gm of radium will reduce to 0.25 gm ?

Answer 1

1 gm of Ra will reduce to 0.5 gm in 1620 yrs. 

0.5 gm of Ra will reduce to 0.25 gm in another 1620 yrs.

\(\therefore \) Time taken by 1 gm of Ra to reduce to 0.25 gm = 1620 + 1620 = 3240