Physics 9702 · AS & A Level · Mass defect and nuclear binding energy

Mass defect and nuclear binding energy — practice question

If a neutron is absorbed by a uranium-235 nucleus, this process can be written as the nuclear equation below. $^{235}_{92}\text{U} + ^{1}_{0}\text{n} \rightarrow ^{95}_{42}\text{Mo} + ^{139}_{57}\text{La} + x^{1}_{0}\text{n} + 7^{0}_{-1}\text{e}$
(a(i))[1]

Use the equation to find the value of $x$.

(a(ii))[1]

State the name of the particle indicated by the symbol $^{0}_{-1}\text{e}$.

(b(i))[3]

Figure 8.1 gives some data for the nuclei in the reaction. Use the data in Fig. 8.1 to determine the binding energy, in $\text{u}$, of a uranium-235 nucleus.

(b(ii))[3]

Show that the binding energy per nucleon for a nucleus of uranium-235 is $7.18\,\text{MeV}$.

(c)[2]

The neutron’s kinetic energy before the reaction is negligible. Use the data from (b) to calculate the total energy released in this reaction, in $\text{MeV}$.

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This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: $x=2$

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