Question

solubility of NaF in water is less than that of RbF

Answer 1

Thanks for asking the question.

Solubility of compounds in a group depends upon the lattice energy. Greater the lattice energy, the lesser is their solubility.The lattice energy decreases down the group because it depends upon charge to size ratio. Size increases down the group so the lattice energy decreases and soulubility increases. Hence RbF is more soluble in water than NaF.