Question

a) Three types of radioactive decay occur in nature. Briefly describe them.
b) State the law of radio active decay.

Answer 1

A) Three types of radio active decay occur in nature:

1. Alpha decay is a radioactive process in which a particle with two neutrons and two protons is ejected from the nucleus of a radioactive atom. The particle is identical to the nucleus of a helium atom. Because alpha particles contain two protons, they have a positive charge of two.

2. Beta decay is a radioactive process in which an electron is emitted from the nucleus of a radioactive atom, along with an unusual particle called an antineutrino. The neutrino is an almost massless particle that carries away some of the energy from the decay process. Because this electron is from the nucleus of the atom, it is called a beta particle to distinguish it from the electrons which orbit the atom.

3. Gamma decay, type of radioactivity in which some unstable atomic nuclei dissipate excess energy by a spontaneous electromagnetic process. In the most common form of gamma decay, known as gamma emission, gamma rays (photons, or packets of electromagnetic energy, of extremely short wavelength) are radiated.

B) According to law of radioactive decay:

Number of nuclei decay in a certain time is directly proportional to the total number of nuclei present initially. And number of nuclei decay is directly proportional to time interval. Combining two we get:
$\frac{△N}{N}=-\lambda △t$

Where N = Number of nuclei initially present, $△N$ = Number of nuclei decay and $\lambda$= Decay constant.
After integration we get,
$\frac{△N}{N_0}=e^{-\lambda t}$