Various rules of thumb have seen proposed by the scientific community to expalin the mode of radioactive decay by various radioisotopes. One of the major rules is called the `n//p` ratio. If all the known isotopes of the elemnts are plotted on a graph of number of neutrons (n) versus number of protons (p), it is observed that all isotopes lying outside of a ''stable'' `n//p` ratio region are radioactive as shown fig.5.28. The graph exhibits straight line behaviour with unit slope up to `p=25`. Above `p=25`, tgose isotopes with `n//p` ratios lying above the stable region usually undergo beta decay. Very heavy isotopes `(pgt83)` are unstable because of their relativley large nuclei and they undergo alpha decay. Gamma ray emission does not involve the release of a particle. It represnts a change in an atom from a higher energy level to a lower energy level.

Which of the following represents the relative penetrating power of the three types of radioactive emission in decreasing order?

Options

A. `betagtalphagtgamma`
B. `betagtgammagtalpha`
C. `gammagtalphagtbeta`
D. `gammagtbetagtalpha`

Answer

d

Explanation

Alpha radiation consists of the largest particles (helium nuclei with a mass number of `4`, thus the greatest inertia)and are slowest (about `1//3` times the speed of the light). Beta radiation consists of smaller (electrons, `1//1370` times lighter than a proton) and faster partilces (about `4//5` times the speed of light). Gamma radiation consits of the smallest particles (photons, no mass ) which travel at the greatest speed (at the speed of light).