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 need to analyze each statement based on the definitions of open, closed, and insulated systems.

### Step-by-Step Solution:

1. **Understanding System Types**:
- **Open System**: Both matter and energy can be exchanged with the surroundings.
- **Closed System**: Only energy can be exchanged; matter cannot be exchanged.
- **Insulated System**: Neither matter nor energy can be exchanged with the surroundings.

2. **Analyzing the First Statement**:
- **Statement**: "The presence of reacting species in a covered beaker is an example of open system."
- **Analysis**: A covered beaker does not allow matter to escape, hence it cannot be an open system. This statement is **incorrect**.

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

4. **Analyzing the Third Statement**:
- **Statement**: "The presence of reactants in a closed vessel made up of closed system."
- **Analysis**: A closed vessel allows energy exchange but not matter exchange, which aligns with the definition of a closed system. This statement is **correct**.

5. **Analyzing the Fourth Statement**:
- **Statement**: "The presence of reactants in a thermo flask or any other closed insulated vessel is an example of closed system."
- **Analysis**: A thermo flask is designed to prevent both matter and energy exchange, making it an insulated system, not a closed system. This statement is **incorrect**.

### Conclusion:
The only correct statement is the third one: "The presence of reactants in a closed vessel made up of closed system."