Most of the ratio active elements are in

The most ratioactive element is

20% of a radio active element disintergrates in 1 hr. The percentage of the radio active element disintergrated in 2 hrs will be

The most reactive elements is

Half life of a ratio-active element is 8 years, how much amount will be present after 32 years ?

Half life of a ratio-active element is 8 years, how much amount will be present after 32 years ?

Chemically least active element is

What are unit of activity of radioactive elements?