Question

Which of the following is not a state function?
A.Temperature
B.Density
C.Work
D.Volume

Answer 1

State functions are intrinsic properties of a system. The value of state function depends only upon the initial and final state of the path followed while the value of path function does not depend upon the initial and final state of the path followed.

Complete answer:
This question belongs to the concepts of thermodynamics. First let us see what a state function is. As we know processes in thermodynamics take place along a path. A system goes from one state to another by taking a specified path.
Based upon the applicability of path there are two types of function which are state function and path function. The properties whose value only depend upon the state of the function and not on the path taken to reach a specific path, such properties are known as state functions. The properties whose value does not depend upon the state of the function and only on the path taken to reach a specific path, such properties are known as path functions.
The state functions are capable of integrating using initial and final values but path function requires multiple integral and limit of integral for them to integrate. In state function, any number of steps results in the same value but different steps result in different values in the path function. There are seven known state functions which are pressure, temperature, volume, mass, internal energy, gibbs free energy and entropy.
Therefore work is not a state function as it strictly depends upon the path taken by a process. If a process has to take an alternative path for doing the same work then it will alter the nature and magnitude of work significantly.

So, option C is the correct answer.

Note:
Whenever analysing a state function we have to take care whether the path taken affects the value. State functions are useful in the use of Hess’s law which allows algebra of enthalpies of half reactions which adds to form a full reaction.