Why should a radioactive substance not be touched by hands?

What do you mean by background radiations? Name it's two sources. Is it possible for us to keep ourselves away from it?

What is nucleus of an atom? Compare it's size with that of the atom. Name it's constituents. How is the number of these constituents determined by the atomic number and mass number of an atom?

A radioactive source emits three types of radiations.

(a) Name the three radiations.

(b) Name the radiations which are deflected by the electric field.

(c) Name the radiation which is most penetrating.

(d) Name the radiation which travels with the speed of light.

(e) Name the radiation which has the highest ionizing power.

(f) Name the radiation consisting of the same kind of particles as the cathode rays.