The curve between the activity $A$ of a radioactive sample and the number of active atoms $N$ is

In a radioactive material, fraction of active material remaining after time $t$ is $\frac{9}{16}$ The fraction that was remaining after $\frac{t}{2}$ is 

$x$ fraction of a radioactive sample decay in $t$ time. How much fraction will decay in $2t$ time

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?

A radioactive element $ThA (_{84}Po^{216})$ can undergo $\alpha$ and $\beta$ are type of disintegrations with half-lives, $T_1$ and $T_2$ respectively. Then the half-life of ThA is

Radioactive element decays to form a stable nuclide, then the rate of decay of reactant is