Answer:
ΔS depends not merely on q but on qrev. Although there are many possible paths that could take a system from its initial to final state, there is always only one reversible isothermal path between two states. Thus, ΔS has only one particular value regardless of the path taken between states.
Step-by-step explanation:
A reversible process is one carried out in infinitesimal steps after which both the system and surroundings remain unchanged.
The sum of the heat (q) and work (w) associated with a process is a state function defined by the First Law ΔU = q + w. Heat and work themselves are not state functions, and therefore depend on the particular pathway in which a process is carried out.
As a process is carried out in a more reversible manner, the value of w approaches its maximum possible value, and q approaches its minimum possible value.
Although q is not a state function, the quotient qrev/T is, and is known as the entropy.