Answer
See answers.
Work Step by Step
These are discussed in section 31-3.
a. The binding energy per nucleon grows with the number of nucleons (up to a certain point). Therefore, when two small nuclei undergo fusion, the total energy of the larger nucleus is less than the starting energy of the two nuclei, and the excess energy is released.
b. The first reaction (equation 31-6a) has a much smaller chance of occurring than the other reactions in the proton-proton chain. So, the rate at which that first reaction takes place limits the rate at which the sun produces energy.
c. According to Figure 31-12 and the text, the heaviest elements are those with $A\approx 60$, e.g., iron is commonly cited.
d. Gravitational attraction holds the atoms in the sun (or in a star) together (page 897).
e. The two methods are (i) magnetic confinement, such as in a tokamak, using magnetic fields to contain the nuclei that are fused, and (ii) inertial confinement, using powerful lasers and striking the fusion material simultaneously from hundreds of directions. This fuses the atoms so rapidly that the nuclei have no time to move apart.
