Previous Year Questions
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- Practice Previous Year questions to get a better idea of the CBSE exam.
In decay, a
neutron converts into a proton emitting antineutrino.
neutron converts into a proton emitting neutrino.
proton converts into a neutron emitting antineutrino.
proton converts into a neutron emitting neutrino.
When two nuclei fuse together to form a heavier nucleus, the
binding energy per nucleon increases.
binding energy per nucleon decreases.
binding energy per nucleon does not change.
total binding energy decreases.
For a radioactive substance, show the variation of the total mass disintegrated as a function of time t graphically.
Initial mass of a radioactive substance is 3.2 mg. It has a half-life of 4 h. Find the mass of the substance left undecayed after 8 h. 
Differentiate between half life and average life of a radioactive substance. 
A radioactive substance decays for an interval of time equal to its mean life. Find the fraction of the amount of the substance which is left undecayed after this time interval.
Plot a graph showing the variation of undecayed nuclei versus time . From the graph, find out how one can determine the half-life and average life of the radioactive nuclei.
Write two distinguishing feature of nuclear forces.
Complete the following nuclear reaction for and decay:
(a) Explain the processes of nuclear fission and nuclear fusion by using the plot of binding energy per nucleon (BE/A) versus the mass number .
(b) A radioactive isotope has a half-life of years. How long will it take for the activity to reduce to %?
Four nuclei of an element undergo fusion to form a heavier nucleus, with release of energy. Which of the two - the parent or the daughter nucleus - would have higher binding energy per nucleon?
(a) Derive the mathematical expression for law of radioactive decay for a sample of a radioactive nucleus.
(b) How is the mean life of a given radioactive nucleus related to the decay constant?
Distinguish between nuclear fission and fusion. Show how in both these processes energy is released. Calculate the energy release in MeV in the deuterium-tritium fusion reaction : 

Using the data:

Write symbolically the nuclear decay process of . Is the decayed product X an isotope or isobar of ()? Given the mass values m () = 11.011434 u and m (X) = 11.009305 u. Estimate the Q-value in this process.