The radioactive sources $A$ and $B$ have half lives of $2\ hr$ and $4\ hr$  espectively, initially contain the same number of radioactive atoms. At the end of $2\  hours$, their rates of distintegration are in the ratio

A radioactive material has a half-life of $8$ years. The activity of the material will decrease to about $1/8$ of its original value in .......... $years$

The half-life of a radioactive substance is $20\, min$. The approximate time interval $\left(t_{2}-t_{1}\right)$ between the time $t_{2},$ when $\frac{2}{3}$ of it has decayed and time $t_{1},$ when $\frac{1}{3}$ of it had decayed is (in $min$)

The curve between the activity $A$ of a radioactive sample and the number of active atoms $N$ is

A nuclear power plant supplying electrical power to a village uses a radioactive material of half life $T$ years as the fuel. The amount of fuel at the beginning is such that the total power requirement of the village is $12.5 \%$ of the electrical power available form the plant at that time. If the plant is able to meet the total power needs of the village for a maximum period of $n T$ years, then the value of $n$ is

How much mass of uranium to be destroyed per minute to operate a nuclear reactor of $600\,MW$