The correct relation is

Options

A. `DeltaG-RT" ln "K//Q`
B. `DeltaG=-RT" ln "K`
C. `DeltaG=-RT" ln "Q//K`
D. `DeltaG=+RT" ln "Q`

Explanation

To solve the question regarding the correct relation involving Gibbs free energy change (ΔG), we will follow these steps:

### Step-by-Step Solution:

1. **Understanding Gibbs Free Energy Change**:
- The Gibbs free energy change (ΔG) indicates the spontaneity of a reaction. If ΔG is negative, the reaction is spontaneous; if positive, it is non-spontaneous.

2. **Standard Gibbs Free Energy Change**:
- The standard Gibbs free energy change (ΔG°) is defined for reactions under standard conditions (1 bar pressure, 1 M concentration). It can be calculated using the formula:
\[ \Delta G° = -RT \ln K \]
where \( R \) is the universal gas constant, \( T \) is the temperature in Kelvin, and \( K \) is the equilibrium constant.

3. **Gibbs Free Energy Change for Non-Standard Conditions**:
- For reactions that are not at equilibrium, the Gibbs free energy change is given by:
\[ \Delta G = \Delta G° + RT \ln Q \]
where \( Q \) is the reaction quotient, which reflects the current concentrations of reactants and products.

4. **Combining the Equations**:
- We can substitute the expression for ΔG° into the equation for ΔG:
\[ \Delta G = -RT \ln K + RT \ln Q \]
- This can be rearranged to:
\[ \Delta G = RT (\ln Q - \ln K) = RT \ln \left(\frac{Q}{K}\right) \]

5. **Identifying the Correct Relation**:
- From the derived equation, we see that ΔG is related to the ratio of the reaction quotient to the equilibrium constant:
\[ \Delta G = RT \ln \left(\frac{Q}{K}\right) \]
- Therefore, the correct relation among the given options is likely to be the one that matches this derived equation.

### Conclusion:
- Based on the analysis, the correct answer is **Option C**, which corresponds to the relation we derived.