(a(i))[4]
The isotopes uranium-235 ($^{235}_{92}\text{U}$) and uranium-238 ($^{238}_{92}\text{U}$) are two forms of uranium. Describe in detail an atom of uranium-235.
(a(ii))[2]
Using the two forms of uranium, explain the term isotopes.
(b(i))[2]
After a uranium-235 nucleus absorbs a neutron, the following reaction may occur: $^{235}_{92}\text{U} + ^{w}_{x}\text{n} \rightarrow ^{148}_{57}\text{La} + ^{z}_{y}\text{Q} + 3^{w}_{x}\text{n}$. Determine the values of $Y$ and $Z$.
(b(ii))[2]
Explain why the combined masses of the uranium nucleus and the neutron are not the same as the total mass of the reaction products.