Question

A well stoppered Thermo flask contains some ice cubes. This is an example of:
(A) Closed system
(B) Open system
(C) Isolated system
(D) Non – thermodynamic system

Answer 1

Hint: To answer this you must know the definitions of the system mentioned in the options. Remember that a Thermo flask creates a vacuum-like environment thus disables any transformation of energy or matter. Use this to answer the given question.

Complete step by step solution:
To answer this question, firstly let us discuss the systems mentioned in the options and then we will identify the correct answer.
Firstly we have a closed system. A system in which energy can be exchanged from its surroundings in the form of heat or work but there is no exchange of matter is known as a closed system.
Then we have an open system. A system in which energy, as well as matter, can be exchanged between the surrounding and the system is known as an open system.
Next, we have an isolated system. A system where no exchange is taking place between the system and the surrounding is known as an isolated system. In such a system, neither matter nor energy is exchanged from the surroundings.
And lastly, we have a non – thermodynamic system. A system which is not in a state of thermodynamic equilibrium is known as a non-thermodynamic system.
Now, let us see the question given to us.
Here we have ice cubes in a Thermo flask. We know that a Thermo flask is a container lined with insulating material which creates an environment similar to a vacuum. In a thermos flask, we do not notice any change in temperature or the matter for a long time i.e. neither energy nor matter is exchanged.

Therefore, the correct answer is option (C) Isolated system.

Note: The definition of open and closed systems come from the first law of thermodynamics. According to the first law of thermodynamics, if a system is subjected to any cyclic transformation, the sum of heat and work involved is zero. \[\oint{dq+\oint{dw=0}}\]
As work is done and heat energy both are a path function, their cyclic integration is zero thus, the above statement holds true.