) consisting of two protons and two neutrons is known as alpha particle. Beta particles are electrons ( - e ), which are the basic elementary particles present in all atoms. Gamma rays are electromagnetic waves consisting of photons. A nuclear reaction in which an unstable parent nucleus emits an alpha particle and forms a stable daughter nucleus is called as 'alpha decay'.
A nuclear reaction in which an unstable parent nucleus emits a beta particle and forms a stable daughter nucleus is called as 'beta decay'. The process of breaking (splitting) up of a heavier nucleus into two smaller nuclei with the release of a large amount of energy is called 'nuclear fission'. The energy released in a nuclear fission process is about MeV. There are some radioactive elements which can be converted into a fissionable material.
They are called as ' fertile materials '. e.g. Uranium- , Thorium- , Plutonium- . Controlled chain reaction is used in a nuclear reactor to produce energy in a sustained and controlled manner.
The process in which two lighter nuclei combine to form a heavier nucleus is termed as 'nuclear fusion'. Nuclear fusion or thermonuclear reaction is the source of light and heat energy in the Sun and other stars. The safe limit of receiving the radiation is about mR per week. I.
Choose the correct answer . Man-made radioactivity is also known as a. Induced radioactivity b. Spontaneous radioactivity c.
Artificial radioactivity d. a & c . Unit of radioactivity is a. roentgen b.
curie c. becquerel d. all the above . Artificial radioactivity was discovered by TEXTBOOK EVALUATION a.
Bequerel b. Irene Curie c. Roentgen d. Neils Bohr .
In which of the following, no change in mass number of the daughter nuclei takes place i) α decay ii) β decay iii) γ decay iv) neutron decay a. (i) is correct b. (ii) and (iii) are correct c. (i) & ( iv) are correct d.
(ii) & (iv) are correct . isotope is used for the treatment of cancer.