The amount of $_{53}I^{128}$ $(t_{1/2} = 25 \ min)$ remaining after $75 \ min$ is:

The half-life of a radionuclide is $69.3 \text{ minutes}$. What is its average life (in minutes)?

The disintegration constant for a radioactive substance is $0.58 \, hr^{-1}$. Its half-life period is $........ \, hr$.

$A$ radioactive sample has a half-life of $1500 \ years$. $A$ sealed tube containing $1 \ g$ of the sample will contain after $3000 \ years$:

The half-life of a radioactive substance is $120$ days. After $480$ days,the amount of $4 \ g$ of the substance remaining will be: (in $g$)

$A$ radioactive element has a half-life of $1 \text{ day}$. After $3 \text{ days}$,the amount of the element left will be: