The correct statement among the following is:
| 1. | The presence of reacting species in a covered beaker is an example of an open system. |
| 2. | There is an exchange of energy as well as matter between the system and the surroundings in a closed system. |
| 3. | The presence of reactants in a closed vessel made up of copper is an example of a closed system. |
| 4. | The presence of reactants in a thermos flask or any other closed insulated vessel is an example of a closed system. |
