Solution:

(I) The measures of Be2+ and O2-are little and are profoundly viable with one another. Because of this, a high measure of cross section energy is delivered during its arrangement. The hydration energy, when it is made to break down in water, isn’t sufficient to defeat the grid energy. In this way, BeO is practically insoluble in water.

While the size of a SO42-is huge contrasted with Be2+ and there is lesser similarity and grid energy which can be effectively overwhelmed by the hydration energy. In this way, BeSO4 is effectively dissolvable in water.

(ii) The extents of Ba2+ and SO42-are huge and are profoundly viable with one another. Because of this, a high measure of grid energy is delivered during its development. The hydration energy, when it is made to break down in water, isn’t sufficient to conquer the grid energy. In this manner, BaSO4 is insoluble in water.

Though the size of an O2-is little contrasted with Be2+ and there is lesser similarity and grid energy which can be effectively overwhelmed by the hydration energy. Hence, BaO is effectively solvent in water.

(iii) The lithium-particle has a more modest size and because of that, it has a higher polarizing ability. This empowers it to captivate the electron cloud around an iodide particle consequently bringing about a more noteworthy covalent person in LiI than KI. In this way, LiI is effectively dissolvable in ethanol.