21. Solid KF has a lattice energy of -804 kJ/mol and a heat of solution (in water) of -15 kJ/mol. RbF has a lattice energy of -768 kJ/mol and a heat of solution (in water) of -24 kJ/mol. Which salt forms stronger attractions with water? (A) KF, because it has a more exothermic lattice energy (B) RbF, because it has a less exothermic lattice energy (C) KF, because it has a more negative heat of hydration (D) RbF, because it has a more negative heat of hydration (E) they form equally strong attractions with water, because they both have negative heats of mixing