Two radio active substances X and Y originally have N1 and N2 nuclei respectively . Half life of X is half of the half life of Y . After three half lives of Y . number of nuclei of both are equal . The ratio N1/N2 will be equal to
1) 1/8
2)3/1
3)8/1
4)1/3

Two radioactive substance X and Y initially contain equal number of nuclei. X has a half life of 1 hour and Y has a half-life of 2 hours. After 2 hours the ratio of activity of X to that of y is

There are two radioactive substance A and B . Decay consant of B is two times that of A . Initially, both have equal number of nuceli. After n half-lives of A ,rates of disintegaration of both are equal. The value of n is .

Half-life of a radioactive substance A is two times the half-life of another radioactive substance B . Initially, the number of A and B are N_(A) and N_(B) , respectively . After three half-lives of A , number of nuclei of both are equal. Then, the ratio N_(A)//N_(B) is .

Two radioactive substances have half-lives T and 2T. Initially, they have equal number of nuclei. After time t=4T , the ratio of their number of nuclei is x and the ratio of their activity is y. Then,

Two radioactive substances X and Y initially contain equal number of atoms. Their half-lives are 1 hour and 2 hours respectively. Calculate the ratio of their rates of disintegration after four hours.

The half lives of radioactive elements X and Y are 3 mintue and 27 minute respectively. If the activities of both are same, then calculate the ratio of number of atoms of X and Y.

Two radioactive substances X and Y initially contain an equal number of atoms. Their half-lives are 1 hour and 2 hours respectively. Then the ratio of their rates of disintergration after two hours is

Two radioactive samples of different elements (half-lives t_1 and t_2 respectively) have same number of nuclei at t=0 . The time after which their activities are same is

The number of nuclei of two radioactive substance is the same and their half-lives are 1 year and 2 years respectively. The ratio of their activities after 6 years will be

Half-life of a radioactive substance A and B are, respectively, 20 min and 40min . Initially, the samples of A and B have equal number of nuclei. After 80 min , the ratio of the ramaining number of A and B nuclei is