Which one of the following is true for the flow of water from high level to low level (at constant temperature and pressure)?

The flow of water from a high level to a low level is a spontaneous process driven by the reduction of gravitational potential energy. In thermodynamics, the spontaneity of a process at constant temperature and pressure is determined by the change in Gibbs free energy (ΔG). For any spontaneous process, the change in Gibbs free energy must be negative (ΔG < 0) [t1][t5]. This negative value indicates that the system is moving toward a more stable state and can perform useful work, such as turning a turbine to generate electricity [c3][t1]. Conversely, ΔG = 0 represents a state of equilibrium where no net change occurs [t5]. Since water naturally flows downward without external energy input, it satisfies the condition for spontaneity, meaning the free energy of the final state is lower than the initial state, resulting in a negative ΔG [t1][t8].

Sources

1. [1] https://www.sciencedirect.com/topics/engineering/gibbs-free-energy
2. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > 22.4. HYDRO POWER > p. 291