The pair of compounds which can not exist together in aqueous solution is : — s Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: The solubility of an ionic compound in water requires the hydration enthalpy of its ions to overcome the lattice enthalpy of the crystal. Step 2: Lithium (Li+) and Fluoride (F-) are both exceptionally small ions, allowing them to pack together very tightly in the crystal lattice. Step 3: This tight packing results in an extraordinarily high lattice enthalpy that cannot be compensated by hydration, making LiF the least soluble of the alkali metal fluorides. Thus, option (b) is correct.