When the surface of the liquid increases due to external action, some of the molecules from the inner regions of the liquid are transferred to its surface. With such a transition, work is performed against the forces of attraction acting on the molecules passing into the surface layer. It is known from mechanics that when performing work against the forces of attraction, the potential energy of the body being moved increases. Therefore, molecules on the surface of a liquid have more energy than the same molecules inside a liquid.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.