A well stopped thermos flask contains ice cubes. This is an example of
Which of the following statement is correct? (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.