Chemistry - PERIODIC TABLE Question with Solution | TestHub

The question asks to identify the option with an incorrect solubility order. Let's analyze each option:

A. $LiF<CsF$: Lithium fluoride (LiF) has lower solubility than Cesium fluoride (CsF). This is generally correct. For alkali metal fluorides, solubility increases down the group due to the decreasing lattice energy outweighing the decreasing hydration energy.

B. $Ca{C}_2{O}_4<Be{C}_2{O}_4$: Calcium oxalate (CaC₂O₄) has lower solubility than Beryllium oxalate (BeC₂O₄). This is generally correct. For alkaline earth metal oxalates, solubility tends to decrease down the group due to decreasing hydration energy of the cation.

C. $AgBr<AgF$: Silver bromide (AgBr) has lower solubility than Silver fluoride (AgF). This is correct. Silver fluoride is soluble in water, while silver bromide is sparingly soluble. The solubility of silver halides increases in the order $AgI<AgBr<AgCl<AgF$.

Since all given options (A, B, C) present correct solubility orders, the compound having an incorrect solubility order is "None of these".

The final answer is $\boxed{D}$