ANS:B - At equilibrium, ΔG is zero.

The correct statement is: "For the reaction, PCl5PCl3 + Cl2, ΔG is less than ΔE." This statement is consistent with the relationship between Gibbs free energy change (Δ𝐺ΔG) and the change in internal energy (Δ𝐸ΔE) for a reaction. If Δ𝐺ΔG is less than Δ𝐸ΔE, it implies that the reaction is spontaneous because the system can do work on the surroundings, which is a characteristic of spontaneous processes. The other statements are incorrect:

1. Heat of solution can be positive or negative depending on whether the process is exothermic or endothermic.
2. At equilibrium, Δ𝐺ΔG is zero for a reversible process, not Δ𝐸ΔE. Δ𝐸ΔE can be zero at equilibrium, but it's not necessarily the case.
3. This statement is incorrect based on the second law of thermodynamics, which states that Δ𝐺ΔG is less than or equal to Δ𝐸ΔE for all processes. Therefore, Δ𝐺ΔG cannot be less than Δ𝐸ΔE.
4. The heating of water in a beaker is an example of an open system because heat can flow between the water and its surroundings. An isolated system doesn't exchange matter or energy with its surroundings.