The mass of a proton is 1.0073 u and that of the neutron is 1.0087 u (u = atomic mass unit) The binding energy of H2e42He4 is (mass of helium nucleus = 4.0015 u)

1. 28.4 MeV

2. 0.061 u

3. 0.0305 J

4. 0.0305 erg

Subtopic:  Mass-Energy Equivalent |
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The binding energies of the nuclei A and B are Ea and EbEa and Eb respectively. Three atoms of the element B fuse to give one atom of element A and an energy Q is released. Then Ea, EbEa, Eb and Q are related as:

1. Ea-3Eb=QEa3Eb=Q 

2. 3Eb-Ea=Q3EbEa=Q

3. Ea+3Eb=QEa+3Eb=Q 

4. Eb+3Ea=QEb+3Ea=Q

Subtopic:  Nuclear Binding Energy |
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A free neutron decays into a proton, an electron and:

1. A beta particle.

2. An alpha particle.

3. An antineutrino.

4. A neutrino.

Subtopic:  Types of Decay |
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In a radioactive sample the fraction of initial number of radioactive nuclei, which remains undecayed after n mean lives is:

1. 1en1en 

2.  enen   

3. 1-1en11en 

4. (1e-1)n(1e1)n

Subtopic:  Radioactivity (OLD NCERT) |
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The activity of a radioactive sample is measured as 9750 counts/min at t = 0 and as 975 counts/min at t = 5 min. The decay constant is approximately:

1. 0.922/min           

2. 0.691/min         

3. 0.461/min           

4. 0.230/min

Subtopic:  Radioactivity (OLD NCERT) |
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The energy equivalent of one atomic mass unit is:
1. 1.6×1019 J1.6×1019 J
2. 6.02×1023 J6.02×1023 J
3. 931 MeV931 MeV
4. 9.31 MeV9.31 MeV

Subtopic:  Mass-Energy Equivalent |
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Solar energy is due to:

1. fusion reaction. 2. fission reaction.
3. combustion reaction. 4. chemical reaction.
Subtopic:  Nuclear Energy |
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At time t = 0, N1 nuclei of decay constant λ1 and N2 nuclei of decay constant λ2 are mixed. The decay rate of the mixture is:

1. -N1N2e-(λ1+λ2)tN1N2e(λ1+λ2)t 

2. -(N1N2)(N1N2) e-(λ1+λ2)te(λ1+λ2)t 

3. -(N1λ1e-λ1t)(N1λ1eλ1t) ++ N2λ2e-λ2tN2λ2eλ2t 

4. -N1λ1N2λ2e-(λ1+λ2)tN1λ1N2λ2e(λ1+λ2)t

Subtopic:  Radioactivity (OLD NCERT) |
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A nucleus XmnmnX emits one αα and two β-βparticles. The resulting nucleus is

1. Xm-4nm4nX 

2. Xm-4n-2m4n2X   

3. Xm-4n-4m4n4X 

4. None of these

Subtopic:  Types of Decay |
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The half-life period of a radioactive substance is 6 h.  If after 24 h, activity is 0.01 μμCi, what was the initial activity? 

1. 0.04 μμCi 

2. 0.08 μμCi

3. 0.24 μμCi 

4. 0.16 μμCi

Subtopic:  Radioactivity (OLD NCERT) |
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