At any instant, the ratio of the amount of radioactive substance is 2:1. If their half lives be respectively 12 and 16 hours, then after two days what will be the ratio of the substances?

The half-life of a radioactive substance is 1,672 years. If the initial mass of the substance is 1 g, after how many years will only 1 mg of it to be left behind?

A sample of radioactive substance is found 90% of its initial amount after one day . What % of the original sample can be found after 3 days?

Two nuclei have mass number in the ratio of 1:2, what is the ratio of their nuclear densities?

A fresh radioactive mixture contians short lived sppecies A and B. Both emitting alpha -particles intially of 8000 alpha particles per minute. 20 minutes later, they emis at the rate of 3500 alpha -particles per minute. If the half-lives of the species A and B are 10 minutes and 500 hours respectively, then the ratio of activities of A: B the intial mixture was:

A radioactive substance decays to 1//32 th initial activity in 25 days.Calculate its half life.

Two wire A & B are of the same metal and are of same length have area of cross section in the ratio of 2:1 If the same potential difference is applied across each wire. What will be the ratio of the current flowing through the wires A & B ?

A certain radioactive substance has a half period of 30 days. What is disintegration constant?

If time t is required for a radioactive substance to become one third of its initial amount, what fraction would be left after 0.5 t ?