If the quantity of a radioactive element is doubled,then its rate of disintegration per unit time will be

The half-life of $_{38}^{90}Sr$ is $20 \text{ years}$. If a sample having an initial activity of $8000 \text{ dis/min}$ is taken,what would be its activity after $80 \text{ years}$?

The half-life of $1 \ g$ of a radioactive sample is $9 \ hours$. The radioactive decay obeys first-order kinetics. The time required for the original sample to reduce to $0.2 \ g$ is .......... $hours$.

The half-life of a radioactive element is $10 \ hours$. How much will be left after $4 \ hours$ in a $1 \ g$-atom sample?

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

The half-life period of a radioactive element is $30 \ min$. One sixteenth of the original quantity of the element will remain unchanged after ........... $min$.