The half life of a radioactive sample undergoing $\alpha$ - decay is $1.4 \times 10^{17}$ s. If the number of nuclei in the sample is $2.0 \times 10^{21}$, the activity of the sample is nearly
$10^{3} \;Bq$
$10^{4}\;Bq$
$10^{5}\;Bq$
$10^{6}\;Bq$
The decay constant of radium is $4.28 \times {10^{ - 4}}$ per year. Its half life will be ..........$years$
The mean life time of a radionuclide, if its activity decrease by $4\%$ for every $1h$ , would be .......... $h$ [product is non-radioactive i.e. stable]
Which of the following Statements is correct?
The graph in figure shows how the count-rate $A$ of a radioactive source as measured by a Geiger counter varies with time $t.$ The relationship between $A$ and $t$ is : $($ Assume $ln\,\, 12 = 2.6)$
The particle that possesses half integral spin as