Question: What are particles formed by the decay of free neutrons?
Answer. A free neutron decays into a proton, a electron and a neutrino.
Question: How the slow neutrons prove to be more effective than the fast neutrons?
Answer. When neutrons travel with energy of 1.2 Mev, they are called fast neutrons but when they move with energy below 1ev are called slow neutrons.The slow neutrons are usually more effective than fast neutrons fission reaction. This is because only slow neutron can be captured by atomic nucleus and nuclear reaction can take place whereas fast neutron cannot be captured.
Question: What is Zeeman effect?
Answer. When the light of spectral lines is passed through the magnetic field, then one spectral line is spltted up into many spectral lines. This splitting of spectral line cannot be explained by Bohr’s theory.
Question: What is stark effect?
Answer. When the light of spectral lines is passed through the electric field, then one spectral line is splited up into many spectral lines. This splitting of spectral line cannot be explained by Bohr’s theory
Question: What are defects of Bohr’s atomic model?
Answer. It only explain the origin the spectrum of monoelectron system i.e of H-atom, He+, Li+2, Be+3 . It does not explain the origin of spectrum of polyelectron system like He, Li, Be. Bohr suggested the circular orbits of electrons around the nucleus of H-atom, but researchers shown that atomic model is not flat rather three dimensional. It does not explain the fine lines in Balmer series. It is also unable to explain the Zeeman Effect and Stark effect.
Question: Why does the fine structure of H-atom in its spectrum find no explanation from Bohr’s model?
Answer. When atomic emission spectrum of hydrogen gas is observed with a high resolving power spectrometer, the individual spectral line looks consisting of several very fine lines in it. Combination of these fine lines also called fine structure can’t be explained by Bohr’s model. This is because, appearance of several lines into single line suggest that only one quantum number is insufficient to explain the several fine lines.
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