Which of the following is not a state variable? A) Pressure B) Heat C) Volume D) Temperature

The correct option is B) Heat.

The state variable is defined as the variable which depends only on the initial and final state irrespective of the final state. Temperature, pressure, volume are examples of state variables.

The parameters or variables are classified as state functions and path functions as defined below:

1. State functions or state variables are those parameters that depend only on the current state of the system and not on the path that they have taken to reach this state.

For e.g: The temperature of the system.

1. path function is a parameter that depends on the path taken by the system to reach the current state.

For, e.g: Work is done by frictional force.