The decay constant of a radio isotope is $\lambda$. If $A_1$ and $A_2$ are its activities at times $t_1$ and $t_2$ respectively, the number of nuclei which have decayed during the time $(t_1 - t_2)$
$A_1t_1-A_2t_2$
$A_1-A_2$
$(A_1-A_2)/λ$
$λ (A_1-A_2)$
Ten percent of a radioactive sample has decayed in $1$ day. After $2$ days, the decayed percentage of nuclei will be ...... $\%$
A radioactive substance has a half-life of $1$ year. The fraction of this material, that would remain after $5$ years will be
The half-life period of radium is $1600 $ years. Its average life time will be.......years
If $10\%$ of a radioactive material decays in $5$ days, then the amount of original material left after $20$ days is approximately ...............$\%$
A radioactive nucleus decays by two different processes. The half life for the first process is $10\, s$ and that for the second is $100 s$. the effective half life of the nucleus is close to$.....sec$