Two radioactive substances P and Q have half-life 6 months and 3 months respectively. Find the ratio of the activity of these two materials after one year.

Two radioactive nuclides A and B have half-lives of 20 and 10 minutes respectively. If starts an experiment with one mole of each of them their mole ratio after a time interval of one hour will be

Two radioactive elements X and Y have half - lives of 6 min and 15 min respectively . An experiment starts with 8 times as many atoms of X as Y . How long it takes for the number of atoms of X left equals the number of atoms of Y left ?

Two elements P and Q have half lives of 10 and 15 minutes respectively. Freshly prepared samples of each isotope initial contain the same number of atoms as each other. After 30 minutes, the ratio of number of P atoms to number of Q atoms will be :

A sample contains 10^(-2) kg of two substances A and B with half lives of 4 and 8 sec repsectively (Given that atomic mass of B is twice of A ). The ratio of average life of A and B is :