Explain the types of physical equilibrium with examples.

(N/A) $(i)$ Solid-Liquid equilibrium: There is only one temperature (melting point) at $1 \ atm$ $(1.013 \ bar)$ at which the two phases can coexist. If there is no exchange of heat with the surroundings,the mass of the two phases remains constant.
$H_{2}O_{(s)} \rightleftharpoons H_{2}O_{(l)}$
Conclusion: Melting point is fixed at constant pressure.
$(ii)$ Liquid-Vapour equilibrium: At a given definite temperature,the vapour pressure is constant between liquid and its vapour in a closed vessel.
$H_{2}O_{(l)} \rightleftharpoons H_{2}O_{(g)}$
Conclusion: At constant temperature,$p_{H_{2}O}$ remains constant in a closed vessel.
$(iii)$ Solid-Gas equilibrium: In a closed vessel,at constant temperature,equilibrium occurs between solid and vapour. This process is known as sublimation.
$NH_{4}Cl_{(s)} \rightleftharpoons NH_{4}Cl_{(g)}$
Conclusion: At constant temperature in a closed vessel,the mass of solid and vapour remains constant.
$(iv)$ Equilibrium involving dissolution of solids in liquids: At constant temperature,a saturated solution of a solid represents a solid-liquid equilibrium where solubility remains constant.
$\text{Solute}_{(s)} \rightleftharpoons \text{Solute}_{(aq)}$ ; $\text{Sugar}_{(s)} \rightleftharpoons \text{Sugar}_{(aq)}$
Conclusion: Concentration of solute in the solution is constant at a given temperature.
$(v)$ Equilibrium involving dissolution of gases in liquids: At constant temperature in a closed vessel,in a saturated solution of gas in liquid,equilibrium is established between the dissolved gas and the free gas. The concentration of gas in the liquid is directly proportional to the pressure of the gas.
$\text{Gas}_{(g)} \rightleftharpoons \text{Gas}_{(aq)}$ ; $CO_{2(g)} \rightleftharpoons CO_{2(aq)}$
Conclusion: The ratio $\frac{[\text{Gas}_{(aq)}]}{[\text{Gas}_{(g)}]}$ is constant at a given temperature.