Question

Thermos flask containing tea is an example of:

• A. Isolated system
• B. Open system
• C. Closed system
• D. None

Answer 1

The correct option is A

Isolated system

Let's talk about the different kinds of system first.
Open system - In an open system matter and energy both can be transferred.
Closed system - In a closed system only energy can be transferred.
Isolated - In an isolated system neither energy nor matter can be transferred.

Now let's take a look at our system.

Firstly, thermos flask is a closed vessel because of which there is no exchange of matter between system and surroundings. Secondly, thermos flask is made up of insulating material which does not allow heat exchange thus maintaining the tea hot. Thus since there is no exchange of heat and matter between system and surroundings it is called an isolated system.