Which of the following statement is correct

Options

A. The presence of reacting species in a covered beaker is an example of open system
B. There is an exchange of energy as well as matter between the system and the surroundings in a closed system
C. The presence of reactants in a closed vessel made up of copper is an example of a closed system
D. The presence of reactants in a thermos flask or any other closed insulated vessel is an example of a closed system

Explanation

To determine which statement is correct regarding thermodynamic systems, let's analyze each statement step by step.

### Step 1: Understand the Types of Thermodynamic Systems
1. **Open System**: In an open system, both energy and matter can be exchanged with the surroundings.
2. **Closed System**: In a closed system, energy can be exchanged with the surroundings, but matter cannot.
3. **Insulated System**: In an insulated system, neither energy nor matter can be exchanged with the surroundings.

### Step 2: Analyze Each Statement

**Statement 1**: "The presence of reacting species in a covered beaker is an example of an open system."
- A covered beaker does not allow matter to escape (the reacting species are contained), but energy can still be exchanged. Therefore, this is an example of a closed system, not an open system.
- **Conclusion**: This statement is **incorrect**.

**Statement 2**: "There is an exchange of energy as well as matter between the system and the surrounding in a closed system."
- By definition, a closed system does not allow matter to be exchanged with the surroundings. It only allows energy exchange.
- **Conclusion**: This statement is **incorrect**.

**Statement 3**: "The presence of reactants in a closed vessel made up of copper is an example of a closed system."
- A closed vessel, regardless of the material (copper in this case), does not allow matter to escape. Thus, it is indeed an example of a closed system.
- **Conclusion**: This statement is **correct**.

**Statement 4**: "The presence of reactants in a thermos flask or any other closed insulated system is an example of a closed system."
- A thermos flask is designed to be insulated, meaning it does not allow energy or matter exchange. Therefore, it is an insulated system, not a closed system.
- **Conclusion**: This statement is **incorrect**.

### Final Conclusion
The only correct statement among the options provided is **Statement 3**: "The presence of reactants in a closed vessel made up of copper is an example of a closed system."

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