Water potential of a solution at room temperature and pressure

Solution:

Water potential ($\Psi_w$) is the potential energy of water per unit volume relative to pure water at standard conditions. Pure water at standard temperature and pressure has a water potential of zero ($\Psi_w = 0$). When a solute is added to pure water, the concentration of water decreases, and the free energy of water molecules decreases. This results in a decrease in water potential. The solute potential ($\Psi_s$) is always negative for a solution. Water potential is the sum of solute potential and pressure potential ($\Psi_w = \Psi_s + \Psi_p$). For an open solution at atmospheric pressure, the pressure potential ($\Psi_p$) is zero. Therefore, the water potential of a solution is equal to its solute potential ($\Psi_w = \Psi_s$). Since $\Psi_s$ is always negative, the water potential of a solution is always less than zero. Option (1) is incorrect because the water potential of a solution is less than pure water. Option (2) is incorrect because adding more solute makes the solute potential more negative, thus decreasing the water potential. Option (4) is incorrect because adding pure water to a solution decreases the solute concentration, making the solute potential less negative (closer to zero), thus increasing the water potential.