(a)[2]
State what the mass defect of a nucleus means.
(b)[4]
Table 9.1 lists the masses of the nuclides taking part in this reaction. Calculate the energy released when $1.00$ mol of helium-4 is formed.
(c(i))[2]
The star Sirius has a radius of $1.19 \times 10^{9}\,\mathrm{m}$ and is losing mass through nuclear fusion at a rate of $1.09 \times 10^{11}\,\mathrm{kg\,s^{-1}}$. Assume that the power of the radiation emitted by the star is equal to the power released by this process. Determine the luminosity of Sirius. Include a unit in your answer.
(c(ii))[2]
Use your answer in part (c)(i) to find the surface temperature of Sirius.
(d)[3]
Explain how cosmologists use standard candles to estimate the distance of a galaxy from the Earth.