The half life of radioactive Radon is $3.8$ days. The time at the end of which $1/{20^{th}}$ of the Radon sample will remain undecayed is ........... $day$ (Given ${\log _{10}}e = 0.4343$)

The average life $T$ and the decay constant $\lambda $ of a radioactive nucleus are related as

A radioactive material of half-life $T$ was produced in a nuclear reactor at different instants, the quantity produced second time was twice of that produced first time. If now their present activities are $A_1$ and $A_2$ respectively then their age difference equals :

A radioactive nucleus decays by two different process. The half life of the first process is $5$ minutes and that of the second process is $30\,s$. The effective half-life of the nucleus is calculated to be $\frac{\alpha}{11}\,s$. The value of $\alpha$ is $..............$

The half-life of ${ }^{198} {Au}$ is $3 \,days.$ If atomic weight of ${ }^{198} {Au}$ is $198\, {g} / {mol}$ then the activity of $2 \,{mg}$ of ${ }^{198} {Au}$ is ..... $\times 10^{12}\,disintegration/second$

A small quantity of solution containing $Na^{24}$ radio nuclide of activity $1$ microcurie is injected into the blood of a person. A sample of the blood of volume $1\, cm^3$ taken after $5$ hours shows an activity of $296$ disintegration per minute. What will be the total volume of the blood in the body of the person. Assume that the radioactive solution mixes uniformly in the blood of the person ......... $liter$

(Take $1$ curie $= 3.7 × 10^{10}$ disintegration per second and ${e^{ - \lambda t}} = 0.7927;$ where $\lambda$= disintegration constant)