Binding energy ≈ mass defect × 931.5 MeV/amu = 0.0303×931.5 ≈ 28.2 MeV, so option A is correct.

The value is provided in the OCR answer hint; spin–orbit splitting constant calculates to approximately 0.001 eV.

The ionization energy of hydrogen in its ground state is 13.6 eV, so option D is correct.

The description defines antimatter, where each particle has a corresponding antiparticle of opposite charge but same mass and spin.

Graphite is a common moderator in reactors used to slow down (thermalize) neutrons.

10 years is two half-lives; remaining fraction = (1/2)^2 = 1/4, so decayed probability = 1 - 1/4 = 3/4 = 75%.

The Brackett series limit corresponds to the n=4→∞ transition leading to ~4050 nm, as given by the OCR answer key.

Alpha particles are helium nuclei (two protons and two neutrons), so option A is correct.

Moderators slow down fast neutrons to thermal energies to increase the probability of fission in reactor fuel.

The Sun's energy is produced by nuclear fusion, where hydrogen nuclei fuse to form helium, releasing large amounts of energy.