Which of the following expressions is not acceptable?
(i) `Delta P = P_(f) - P_(i)`
(ii) `Delta_(w) = w_(f) - w_(i)`
(iii) `Delta q = q_(f) - q_(i)`
(iv) `Delta U = U_(f) - U_(i)`

Options

A. (i),(ii)
B. (ii),(iii)
C. (iii),(iv)
D. (i),(iv)

Answer

B

Explanation

We cannot write `Delta w = w_(f) - w_(i)` because work is not a state function. Thus, work done not only depends on the initial state and final state, but also depends on how we carry out the process. Similarly, we cannot write `Delta q = q_(g) - q_(i)` because heat is not a state function. Like work, the heat associated with a given process depends on how process is carried out.