After $1$ hour,$1/16$ of the radioactive substance remains. Its half-life is ....... minutes.

The half-life of a radioactive nucleus is $5$ years. The fraction of the original sample that would decay in $15$ years 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 from 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

The half-life of a radioactive substance is $12 \text{ minutes}$. The time gap between $28 \%$ decay and $82 \%$ decay of the radioactive substance is

The decay constant of radium is $4.28 \times 10^{-4}$ per year. Its half-life will be .......... $years$.

$A$ radioactive sample with a half-life of $1$ month has the label: "Activity $= 2 \, \mu Ci$ on $1-8-1991$." What will be its activity two months earlier in $\mu Ci$?