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Q 1. If the atomic masses of Lithium, Helium and Proton are 7.01823 amu, 4.00387 amu and 1.00815 amu respectively, calculate the energy that will be evolved in the reaction. .
(Given that 1 amu = 931 MeV)
17.3 MeV
17.8 MeV
17.2 MeV
17.0 MeV
Total mass of the reacting species and
The mass of the resulting species amu
Mass of reacting species converted into energy, i.e., amu
Energy evolved in the reactionMeV.
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Q 2. Calculate the mass defect and binding energy per nucleon for . [The mass of
, mass of hydrogen atom = 1.008142 amu and mass of neutron = 1.008982 amu].
8.77 MeV
8.25 MeV
9.01 MeV
8.00 MeV
Number of protons in
Number of neutrons = 59 - 27 = 32
The binding energy per nucleon
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Q 3. Calculate the number of neutrons in the remaining atom after emission of an alpha particle from atom
146
145
144
143
On account of emission of an alpha particle, the atomic mass is decreased by 4 units and atomic number by 2 units
So, Atomic mass of daughter element = 234
Atomic number of daughter element = 90
Number of neutrons = Atomic mass - Atomic number
= 234 - 90 = 144
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Q 4. Radioactive disintegration of takes place in the following manner into
, Determine mass number and atomic number of RaC.
214 and 84
214 and 86
214 and 83
214 and 85
Parent element is
Atomic mass = 226
Atomic number = 88
RaC is formed after the emission of 3 alpha particles. Mass of 3 alpha particles
So Atomic mass of RaC
With emission of one α-particle, atomic number is decreased by 2 and with emission of β-particle, atomic number is increased by 1.
So Atomic number of RaC
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Q 5. How many 'α and β' particles will be emitted when changes into
2 and 6
4 and 2
2 and 4
6 and 2
The change is;
Decrease in mass
Mass of 1 α-particle
Therefore, number of α-particles emitted
Number of β-particles emitted
Hence number of α-particles = 4 and number of β-particles = 2
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Q 6. The isotopes and
occur in nature in the ratio of 140 : 1. Assuming that at the time of earth formation, they were present in equal ratio, make an estimation of the age of earth. The half life period of
and
are
and
years respectively
years
years
years
years
Let the age of the earth be t years
For
......(i)
For
......(ii) Subtracting eq. (ii) from eq. (i)
years