At some instant, a radioactive sample having an activity has twice the number of nuclei as another sample which has an activity of . The ratio of half lives of is
A radioactive element has a rate of disintegration disintegrations per minute at a particular instant. After four minutes it becomes disintegrations per minute. The decay constant per minute is
An accident in a nuclear laboratory resulted in deposition of a certain amount of radioactive material of half-life days inside the laboratory. Tests revealed that the radiation was times more than the permissible level required for safe operation of the laboratory. What is the minimum number of days after which the laboratory can be considered safe for use?
A radioactive nucleus with a half-life , decays into a nucleus . At , there is no nucleus . At some time , the ratio of the number of to that of is . Then, is given by:
Two species of radioactive atoms are mixed in equal number. The disintegration of the first species is and of the second is . After a long time the mixture will behave as a species with mean life of approximately
Using a nuclear counter the count rate of emitted particles from a radioactive source is measured. At it was counts per second and seconds it was counts per second. The count rate observed, as counts per second, at seconds is close to:
At a given instant, say two radioactive substance and have equal activities. The ratio of their activities after time itself decays with time as If the half-life of is the half-life of is:
A solution containing active cobalt having an activity of and decay constant is injected in an animal's body. When blood is drawn from the animal's body after of injection, the activity was found to be (decays per minute), then the total volume of blood in the animal's body is close to (decays per second) and at the value of
A nuclear decay is possible if the mass of the parent nucleus exceeds the total mass of the decay particles. If denotes the mass of a single neutral atom of an element with mass number A and atomic number Z, then the minimal condition that the decay, , will occur is ( denotes the mass of the particle and the neutrino mass can be neglected):
The half-life of a particle of mass is and a stream of such particles is travelling with the of a particle being . The fraction of particles which will decay when they travel a distance of is,
Radioactive material has decay constant and material has decay constant . Initially they have the same number of nuclei. After what time, the ratio of number of nuclei of material to that will be
In a radioactive decay chain, the initial nucleus is . At the end, there are -particles and -particles which are emitted. If the end nucleus is and are given by:
A sample of radioactive material , that has an activity of has twice the number of nuclei as another sample of a different radioactive material which has an activity of . The correct choices for half-lives of and would then be, respectively:
