1. Which of the following is used as a moderator in nuclear reactor?
A. Thorium
B. Graphite
C. Radium
D. Ordinary water
2. Which among the following is a positively charged particle emitted by a radioactive element?
A. Beta ray
B. Alpha ray
C. Cathode ray
D. Gamma ray
3. Atoms are composed of
A. electrons and protons
B. electrons only
C. protons only
D. electrons and nuclei
4. In an atomic explosion, enormous energy is released which is due to
A. conversion of chemical energy into heat energy
B. conversion of mechanical energy into nuclear energy
C. conversion of mass into energy
D. conversion of neutrons into protons
5. Isotopes are separated by
A. crystallisation
B. sublimation
C. distillation
D. filtration