Enthalpy changes with consistently exothermic signs Steps:

• Define each enthalpy change and its typical sign based on bond breaking/forming.
• Atomisation: always endothermic (breaks metal lattice or bonds to form gaseous atoms).
• Neutralisation: always exothermic (acid-base reaction forms bonds in water).
• Combustion: always exothermic (fuels oxidize, forming strong C=O and O-H bonds).
• Hydration: always exothermic (gaseous ions form attractions with water dipoles).
• Solution: variable sign (for ionic solids, lattice breaking endothermic, hydration exothermic; net depends on magnitudes). Why B is correct:
• Both combustion and hydration always release energy (ΔH < 0), as combustion involves exothermic oxidation and hydration exothermic solvation per Hess's law applications. Why the others are wrong:
• A: Atomisation endothermic, neutralisation exothermic—opposite signs.
• C: Solution can be endothermic or exothermic, hydration always exothermic—not always same.
• D: Identical to C, so solution varies while hydration exothermic—not always same.

Final answer: B