After $280$ days, the activity of a radioactive sample is $6000\, dps$. The activity reduces to $3000\, dps$ after another $140\, days$. The initial activity of the sample in dps is
$6000$
$9000$
$3000$
$24000$
The rate of disintegration of fixed quantity of a radioactive element can be increased by
Two radioactive elements $A$ and $B$ initially have same number of atoms. The half life of $A$ is same as the average life of $B$. If $\lambda_A$ and $\lambda_B$ are decay constants of $A$ and $B$ respectively, then choose the correct relation from the given options.
Which of the following cannot be emitted by radioactive substances during their decay
For a radioactive material, half-life is $10$ minutes. If initially there are $600$ number of nuclei, the time taken (in minutes) for the disintegration of $450$ nuclei is
What is the half-life (in years) period of a radioactive material if its activity drops to $1 / 16^{\text {th }}$ of its initial value of $30$ years?