Solubility of s block halides in water depends upon:

Ionization energy of metal:
The ionization energy of a metal is the energy required to remove an electron from an atom of that metal. In the case of s block elements, the ionization energy is generally low due to the presence of only one or two valence electrons. This low ionization energy allows the metal to easily lose electrons and form positive ions.

Lattice energy of compound:
Lattice energy is the energy released when ions come together to form a solid crystal lattice. In the case of s block halides, the lattice energy depends on the size and charge of the ions. Smaller ions with higher charges will have stronger attractions and therefore higher lattice energies.

Hydration energy of ions:
Hydration energy is the energy released when ions are surrounded by water molecules and form hydrated ions. Water molecules have a dipole moment, with a partially positive hydrogen atom and a partially negative oxygen atom. These partially charged regions of water molecules are attracted to the oppositely charged ions, leading to the formation of hydration shells around the ions. The energy released in this process is called hydration energy.

Both 2 and 3:
The solubility of s block halides in water depends on both the lattice energy of the compound and the hydration energy of the ions.

- The lattice energy determines the strength of the ionic bonds in the compound. If the lattice energy is high, it will require more energy to break these bonds and dissolve the compound in water. Therefore, compounds with high lattice energies tend to have lower solubilities in water.
- On the other hand, the hydration energy determines the strength of the interaction between the ions and water molecules. If the hydration energy is high, the ions will be strongly attracted to the water molecules and will readily dissolve in water. Therefore, compounds with high hydration energies tend to have higher solubilities in water.

The overall solubility of an s block halide in water is influenced by the balance between the lattice energy and the hydration energy. If the hydration energy is greater than the lattice energy, the compound will dissolve readily in water. However, if the lattice energy is greater than the hydration energy, the compound will have low solubility in water.

Therefore, the solubility of s block halides in water depends on both the lattice energy of the compound and the hydration energy of the ions.