1.Which of the following is used as a moderator in nuclear reactor?
Thorium
Graphite
Radium
Ordinary water
2.Which among the following is a positively charged particle emitted by a radioactive element?
Beta ray
Alpha ray
Cathode ray
Gamma ray
3.In an atomic explosion, enormous energy is released which is due to
conversion of chemical energy into heat energy
conversion of mechanical energy into nuclear energy
conversion of mass into energy
conversion of neutrons into protons
4. Isotopes are separated by
crystallisation
sublimation
distillation
filtration
5.Which radioactive pollutant has recently drawn to public, due to its occurrence in the building material?
Thorium
Radium
Plutonium
Radan