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, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding System Types**:
- **Open System**: Can exchange both matter and energy with its surroundings.
- **Closed System**: Can exchange energy but not matter with its surroundings.
- **Isolated System**: Cannot exchange either matter or energy with its surroundings.

2. **Analyzing Option A**:
- **Statement**: "The presence of reacting species in a covered beaker is an example of an open system."
- **Analysis**: A covered beaker allows for energy exchange (temperature changes), but since it is covered, no matter can enter or leave. Therefore, this is not an open system.
- **Conclusion**: This statement is **wrong**.

3. **Analyzing Option B**:
- **Statement**: "There is an exchange of energy as well as matter between the systems and the surrounding in a closed system."
- **Analysis**: In a closed system, only energy can be exchanged, not matter. Therefore, this statement is incorrect.
- **Conclusion**: This statement is **wrong**.

4. **Analyzing Option C**:
- **Statement**: "The presence of reactants in a closed vessel made up of copper is an example of a closed system."
- **Analysis**: A closed vessel allows for energy transfer (since copper is a good conductor), but no matter can escape. This fits the definition of a closed system.
- **Conclusion**: This statement is **correct**.

5. **Analyzing Option D**:
- **Statement**: "The presence of reactants in a thermos flask or any other closed insulated vessel is an example of a closed system."
- **Analysis**: A thermos flask is designed to be insulated, meaning it does not allow for energy exchange either. This describes an isolated system, not a closed system.
- **Conclusion**: This statement is **wrong**.

### Final Conclusion:
The correct statement is **Option C**: "The presence of reactants in a closed vessel made up of copper is an example of a closed system."