1. What is used as a moderator in a nuclear reactor?
Ans: Graphite
2. Atoms are conpocom of which elements?
Ans: Electrons and nuclei
3. What is the wavelength of visible spectrum?
Ans: 3900-7600 angstrom
4. Who suggested that most of the mass of the atom is located in the nucleus?
Ans: Rutherford
5. Nuclear fission is caused by the impact of ---------?
Ans: Neutron