PPSC Physics Topic 7 Modern Physics With Answers

PPSC Physics Topic 7 Modern Physics

Sr. # Questions Answers Choice
1 Which one of the following has maximum frequency. Visible light Gama rays Ultraviolet rays Infrared rays
2 Which of the following is deflected by an electric field. Alpha particles X rays Gama rays Neutrons
3 Which one of the following is a neutron absorber Pb Cd Cu Ag
4 Critical mass is the minimum mass needed for Fusion H-Bomb Chain reaction Binding energy
5 Which of the following is required for maintaining sustained chain reaction. Neutrons Protons Electrons Photons
6 Which one of the following quantities is conserved in a nuclear reactor. Energy only Mass only Momentum only Mass energy and momentum
7 The most suitable material for moderator in a nuclear reactor is. B Cd D2O Uranium
8 Besides U 235 what else is needed for making as atomic bomb. Electons Protons Neutrons Photons
9 Which uranium isotope having the atomic weights as given below is easily fissionable. 234 235 236 238
10 The chemical behavior of an atom is determined by Mass number Number of Isotopes Atomic number Binding energy
11 The charge on a helium nucleus is equal to the charge of. Two electrons Two protons Two neutrons One proton
12 The nucleus of tritium is called. Proton Triton Deuleron Positron
13 The half life of radium -226 is 1620 years 45 x 10<sup>9</sup> years 3.8 days 23.5 minutes
14 A spectroscope sorts out Atoms Molecules Elements Isotopes
15 The half life of uranium -238 is 1620 years 4.5 x 10<sup>9 </sup>years 3-8 days 23.5 minutes
16 The SI unit of decay constant is. m m-1 s-1 N m-1
17 The emission of Beta particle from protonium -218 results in the formation of. Protactinium -231 Thorium -232 Astatine -218 Radon -222
18 The energy of neutrons obtained during a fission reaction is. 0.1 MeV 1 KeV 1 MeV Zero
19 The critical mass of a fissionable material is. 1 kg 10 kg 100 kg 1.,000 kg
20 The necessary condition for nuclear fusion is. High temperature and high pressure. Low temperature and high pressure Low temperature and low pressure High temperature and low pressure.
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