**Explanation:**

**Insolubility of BaSO4 in water is due to the fact that the lattice energy of the compound is greater than the hydration energy.**

**Lattice Energy:**
- Lattice energy is the energy released when 1 mole of an ionic compound is formed from its gaseous ions.
- It is a measure of the strength of the electrostatic forces of attraction between the ions in the crystal lattice.
- The higher the lattice energy, the stronger the forces holding the ions together, and the more difficult it is for the compound to dissolve in a solvent.
- In the case of BaSO4, the lattice energy is high due to the strong electrostatic forces between the Ba2+ and SO42- ions in the crystal lattice.

**Hydration Energy:**
- Hydration energy is the energy released when 1 mole of gaseous ions is hydrated (surrounded by water molecules) to form 1 mole of aqueous ions.
- It is a measure of the strength of the electrostatic forces of attraction between the ions and water molecules.
- The higher the hydration energy, the stronger the forces of attraction between the ions and water molecules, and the more likely the compound is to dissolve in water.
- In the case of BaSO4, the hydration energy is lower than the lattice energy, meaning that the forces of attraction between the ions and water molecules are not strong enough to overcome the strong forces holding the ions in the crystal lattice.

**Overall Explanation:**
- When BaSO4 is added to water, the strong electrostatic forces between the Ba2+ and SO42- ions in the crystal lattice prevent the compound from breaking apart.
- The water molecules are unable to effectively solvate the ions and separate them from the crystal lattice.
- As a result, BaSO4 remains insoluble in water because the lattice energy is greater than the hydration energy.
- It is important to note that BaSO4 does not form hydrogen bonds with water molecules, but this is not the primary reason for its insolubility in water.
- The main factor is the difference in energy between the forces holding the ions in the crystal lattice and the forces of attraction between the ions and water molecules.