The age of a tree is determined using the radio-isotope of:

From $N$ atoms of a radioactive element,$n$ alpha particles are emitted per second. The half-life of the element is ......

$A$ radioactive element decays to form a stable nuclide. The rate of decay of the reactant $\left( \frac{dN}{dt} \right)$ will vary with time $(t)$ as shown in which figure?

Half-lives of two radioactive elements $A$ and $B$ are $30 \text{ minute}$ and $60 \text{ minute}$ respectively. Initially,the samples have an equal number of nuclei. After $120 \text{ minute}$,the ratio of the number of decayed nuclei of $B$ to that of $A$ will be:

The decay constant $\lambda$ of a radioactive sample is the probability of decay of an atom in unit time. Then,

The half-life of a radioactive substance is $T$. The time taken for disintegrating $\frac{7}{8}$th part of its original mass will be