What is solubility? Explain the solubility of a solid solute in a liquid solvent.

(N/A) Solubility of a substance is its maximum amount that can be dissolved in a specified amount of solvent at a specified temperature.
Every solid does not dissolve in a given liquid. While $NaCl$ and sugar dissolve readily in water,naphthalene and anthracene do not. On the other hand,naphthalene and anthracene dissolve readily in benzene but $NaCl$ and sugar do not.
It is observed that polar solutes dissolve in polar solvents and non-polar solutes in non-polar solvents. In general,a solute dissolves in a solvent if the intermolecular interactions are similar in the two,or we may say 'like dissolves like'.
When a solid solute is added to the solvent,some solute dissolves and its concentration increases in solution. This process is known as dissolution.
Some solute particles in solution collide with the solid solute particles and get separated out of solution. This process is known as crystallisation.
$A$ stage is reached when the two processes occur at the same rate. Under such conditions,the number of solute particles going into solution will be equal to the solute particles separating out,and a state of dynamic equilibrium is reached: $Solute + Solvent \rightleftharpoons Solution$.
At this stage,the concentration of solute in the solution will remain constant under the given conditions,i.e.,temperature and pressure. $A$ solution in which no more solute can be dissolved at the same temperature and pressure is called a saturated solution. An unsaturated solution is one in which more solute can be dissolved at the same temperature.
Factors affecting solubility:
$(i)$ Effect of temperature: The solubility of a solid in a liquid is significantly affected by temperature. According to Le Chatelier's Principle,if the dissolution process is endothermic $(\Delta_{sol} H > 0)$,solubility increases with a rise in temperature. If it is exothermic $(\Delta_{sol} H < 0)$,solubility decreases.
$(ii)$ Effect of pressure: Pressure does not have any significant effect on the solubility of solids in liquids because solids and liquids are highly incompressible.