(a) Explain the processes of nuclear fission and nuclear fusion by using the plot of binding energy per nucleon versus the mass number A.
(b) A radioactive isotope has a half-life of 10 years. How long will it take for the activity to reduce to 3·125%?
From the graph, we note that
During nuclear fission
From the graph when we go through from heavy region to the middle region there is a given in binding energy per nucleon which means energy is released
During nuclear fusion
From the graph, when we move from lighter nuclei region to heavier nuclei region there is a gain in binding energy per nucleon. Which means energy is released
b)
Given,
activity after 't' time At = 3.125 %
The law of radioactivity decay is given as
where decay constant
Let ( initial activity) Then,
Taking logarithm on both sides
Therefore the time taken for the activity to reduce to 3.125 % is 50 years