A `beta`-particle emitter has a half life of 60.6 min. At any instant of time, a sample of this element registers 2408 counts per second. Calculate the counting rate after 1.5 hours.

A nucleus has a half-life of 30 minutes. At 3 PM its decay rate was measured as 120,000 counts/sec. What will be the decay rate at 5 PM ?

Using a nuclear counter the count rate of emitted particles from a radioactive source is measured. At t=0 it was 1600 counts per second and t = 8 seconds it was 100 counts per second. The count rate observed, as counts per seconds, at t=6, seconds is close to :

The half-life of a radioactive substance is 60 days. A sample of it contains 1 mole nuclide. Calculate the number of disintegrations in the first second.

Tritium has a half life of 12.5 years against beta decay. What fraction of a sample of pure tritium will remain undecayed after 25 years?

A radioactive source has a half life of 3 hours. A freshly prepared sample of the same emits radiation 16 times the permissible safe value. The minimum time after which it would be possible to work safely with the source is :

A counter rate meter is used ot measure the activity of radioactive sample. At a certain instant the count rate was recorded as 475 counters per minute. Five minutes later, the count rate recorded was 270 counts per minute. Calculate the decay constant and half life period of the sample.

Using a nuclear counter the count rate of emitted particles from a radioactive source is measured. At t = 0 seconds it was 25600 counts per second and t = 8 seconds it was 100 counts per second. The count rate observed, as counts per second, at t = 6 seconds is close to: