According to …….law of thermodynamics, `DeltaS_("total") = +ve`.

Answer

To solve the question regarding which law of thermodynamics states that the total change in entropy (ΔS_total) is positive, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Laws of Thermodynamics**:
- The first step is to recall the different laws of thermodynamics. The first law deals with energy conservation, while the second law is focused on entropy.

2. **Understand the Concept of Entropy**:
- Entropy (S) is a measure of the disorder or randomness in a system. The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time.

3. **State the Second Law of Thermodynamics**:
- According to the second law of thermodynamics, the total change in entropy (ΔS_total) is always greater than or equal to zero. This can be expressed as:
\[ ΔS_{total} = ΔS_{system} + ΔS_{surroundings} \geq 0 \]

4. **Differentiate Between Reversible and Irreversible Processes**:
- In reversible processes, the total change in entropy (ΔS_total) is equal to zero. In irreversible processes, ΔS_total is greater than zero. This indicates that while the entropy can remain constant in reversible processes, it will always increase in irreversible processes.

5. **Conclude with the Answer**:
- Therefore, the law of thermodynamics that states that ΔS_total is positive is the **Second Law of Thermodynamics**.

### Final Answer:
According to the **Second Law of Thermodynamics**, ΔS_total is positive.

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