Mark the correct statement

Options

A. For a chemical reaction to be feasible, `DeltaG` should be zero
B. Entropy is a measure of order in a system
C. For a chemical reaction to be feasible, `DeltaG` should be positive
D. The total energy of an isolated system is constant

Explanation

To solve the question, we need to evaluate each statement provided and determine which one is correct based on our understanding of thermodynamics and thermochemistry.

### Step-by-Step Solution:

1. **Evaluate the first statement**: "For a chemical reaction to be feasible, ΔG should be zero."
- **Analysis**: The Gibbs free energy change (ΔG) indicates the spontaneity of a reaction. For a reaction to be feasible or spontaneous, ΔG must be negative (ΔG < 0). Therefore, this statement is **incorrect**.

2. **Evaluate the second statement**: "Entropy is a measure of order in a system."
- **Analysis**: Entropy (S) is a measure of disorder or randomness in a system. A higher entropy value indicates a more disordered state. Thus, this statement is also **incorrect**.

3. **Evaluate the third statement**: "For a chemical reaction to be feasible, ΔG should be positive."
- **Analysis**: As previously mentioned, for a reaction to be feasible, ΔG must be negative (ΔG < 0). Therefore, this statement is **incorrect**.

4. **Evaluate the fourth statement**: "The total energy of an isolated system is constant."
- **Analysis**: An isolated system does not exchange matter or energy with its surroundings. According to the law of conservation of energy, the total energy of an isolated system remains constant. Hence, this statement is **correct**.

### Conclusion:
The correct statement is: "The total energy of an isolated system is constant."