Q.1: In 1886, E. Goldstein discovered the presence of new radiations in a gas discharge and called them ___________.
a) canal rays
Q.2: J. J. Thomson was awarded the Nobel Prize in Physics in 1906 for his discovery of ____________.
Q.3: ________’s atomic theory suggested that the atom was indivisible and indestructible.
Q.4: Thomson’s model of an atom proposed that ____________________.
a) Atom consists of a positively charged sphere and electrons are embedded in it.
b) Negative and positive charges are equal in magnitude, thus making atoms electrically neutral.
c) Both ‘a’ and ‘b’
Q.5: The mass of ________ is approximately 2000 times as that of the electron.
Q.6: The charge of an electron is _________.
a) plus one
c) minus one
Q.7: ___________ are doubly charged helium ions.
c) alpha particles
Q.8: ___________ is known as the ‘Father of nuclear physics’.
a) E. Rutherford
b) J. J. Thomson
c) Neils Bohr
Q.9: E. Rutherford won the Nobel prize in chemistry in _______.
Q.10: The positively charged centre in an atom is known as ______________.
Q.11: ____________ has no charge and has mass nearly equal to that of a proton.
Q.12: ______________ got a Nobel prize for his work on the structure of atom in 1922.
a) J. J. Thomson
c) Neils Bohr
Q.13: According to Bohr’s model of atom, electrons revolving in __________ orbits do not radiate energy.
Q.14: Neutrons are present in nucleus of all atoms except ___________.
Q.15: The sum of masses of protons and neutrons present in the nucleus gives the mass of an ___________.