Which of the following statements is correct according to the basic concepts of thermodynamics which govern the feasibility of a metallurgical process ?

Options

A. When the value of `DeltaG` is positive for the equation `DeltaG=DeltaH-T DeltaS`, the reaction will proceed.
B. If reactant and products of two reactions are put together and net `DeltaG` is -ve , the overall reaction with occur.
C. On increasing the temperature , the value of `DeltaG` reaction will occur.
D. Feasibility of thermal oxidation of an ore can be established by Ellingham diagram in which a straight line shows the reduction will proceed.

Answer

To determine which statements are correct according to the basic concepts of thermodynamics that govern the feasibility of a metallurgical process, we need to analyze each option based on the principles of Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS).

### Step-by-Step Solution:

1. **Understanding Gibbs Free Energy (ΔG)**:
- The Gibbs free energy change (ΔG) is given by the equation:
\[ \Delta G = \Delta H - T \Delta S \]
- A reaction is considered spontaneous if ΔG is negative.

2. **Analyzing Option 1**:
- Option 1 states: "When the value of ΔG is positive, the reaction will proceed."
- Since a positive ΔG indicates that the reaction is non-spontaneous, this statement is **incorrect**.

3. **Analyzing Option 2**:
- Option 2 states: "If reactants and products of two reactions are put together and net ΔG is negative, the overall reaction will occur."
- This statement is **correct** because if the net ΔG is negative, it indicates that the overall process is spontaneous.

4. **Analyzing Option 3**:
- Option 3 states: "On increasing temperature, the value of ΔG will become more negative, and the reaction will occur."
- This statement is generally **correct** because increasing temperature can affect ΔG, especially if ΔS is positive, making ΔG more negative and thus favoring spontaneity.

5. **Analyzing Option 4**:
- Option 4 states: "The feasibility of thermal oxidation of an ore can be established by the Ellingham diagram, in which the straight line shows the reduction and the reaction will proceed."
- This statement is **incorrect** because the Ellingham diagram represents the stability of oxides and the lines indicate the temperature dependence of the free energy of formation of oxides, not necessarily indicating that a straight line corresponds solely to reduction.

### Conclusion:
- The correct options based on the analysis are **Option 2 and Option 3**.