If a substance with hlaf life `3` days is taken at other place in `12` days. What amount of substance is laft now ?

If a substance with half life 3 days is taken at other place in 12 days. What amount of substance is left now, if it follows first order kinetics

A substance with half life period 4 days is taken to another place in 12 days. The amount of substance left now is

A radioactive substance of half life 138. 6 days is placed in a box . After n days only 20% of the substance is present then the value of n is [ in (5)= 1.61]

Half-life of a radioactive substance is 12.5 h and its mass is 256 g . After what time the amount of remaining substance is 1g ?

Half-life of a radioactive substance is 12.5 h and its mass is 256 g . After what time the amount of remaining substance is 1g ?