The activity of a radioactive sample is measured as $9750$ counts per minute at $t = 0$ and as $975$ counts per minute at $t = 5$ minutes. The decay constant is approximately ............ per minute

The nucleus $_{10}^{23} Ne$ decays by $\beta^{-}$ emission. Write down the $\beta$ -decay equation and determine the maximum kinetic energy of the electrons emitted. Given that

$m\left(_{10}^{23} Ne \right)=22.994466 \;u$

$m\left(_{11}^{23} Na\right) =22.089770\; u$

For a substance the average life for $\alpha$-emission is $1620$ years and for $\beta$ emission is $405$ years. After how much time the $1/4$ of the material remains after $\alpha$ and $\beta$ emission .......$years$

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 $min$)

Number of nuclei of a radioactive substance at time $t = 0$ are $1000$ and $900$ at time $t = 2$ $s$. Then number of nuclei at time $t = 4$ $s$ will be

If the mass of a radioactive sample is doubled, the activity of the sample and the disintegration constant of the sample are respectively