The decay profiles of three radioactive species $A$,$B$ and $C$ are given below:
These profiles imply that the decay constants $k_A$,$k_B$ and $k_C$ follow the order:

The rate of radioactive disintegration at an instant for a radioactive sample of half-life $2.2 \times 10^{9} \ s$ is $10^{10} \ s^{-1}$. The number of radioactive atoms in that sample at that instant is:

$A$ radioactive substance is required to have an activity of $0.01 \mu Ci$ in the human body after $24 \ hours$. The half-life of the radioactive substance is $6 \ hours$. What is the maximum initial activity that can be administered (in $\mu Ci$)?

If $2.0 \ g$ of a radioactive isotope has a half-life of $20 \ hr$,the half-life of $0.5 \ g$ of the same substance is ........ $hr$.

The half-life period $t_{1/2}$ of a radioactive element is $N$ years. The period of its complete decay is

If the amount of radioactive substance is increased three times,the number of atoms disintegrated per unit time would