Short Answer Type(i) Write a balanced equation showing nuclear fission of Uranium 
(ii) In a nuclear reactor, what is the function of:
(1) Cadmium rods? (2) Graphite rods?
On an energy level diagram of hydrogen, show by a downward or an upward arrow, a transition which results in:
(i) Emission line of Balmer series.
(ii) Emission line of Lyman series.
(iii) Absorption line of Lyman series.
and Its binding energy in MeV.
Mass of a proton = 1.007276 u
Mass of a neutron = 1.008665 u
Mass of 
nucleus = 4.001506 u
An α-particle is helium (2He4) nucleus, containing two protons and two neutrons.
We can find out its mass defect from the given data:
Mass of 2 protons = 2 x 1.000728
= 2.01456 u
Mass of 2 neutrons = 2 x 1.00867
= 2.01734u
Total = 4.03190 u.
This is the total mass of the nucleus of α-particle.
The mass of α-particle is 4.00151 u. therefore, the mass defect is
Δm = mass of nucleons-mass of α-particle
= 4.03190 - 4.00151u
= 0.03039 u.
According to the energy mass relation ΔE = (Δm)c2, 1u of mass equivqlent to 931.5 MeV of energy.
Energy equivalent to 0.03039 u is
ΔE = 0.03039X 931.5 = 28.3 MeV.
This is the binding energy of α-particle.
The binding energy per nucleon is 28.3/4 = 7.07Mev.
This large amount of energy explains the high stability of a- particle.
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