The difference in entropy $S_y-S_x$ between states $y$ and $x$ is approximately equal to the ideal gas constant R times what number? $($Hint: Entropy is a property of a gas state, not of the path taken to arrive at that state. Notice that the temperatures at $x$ and $y$ are equal, and try to imagine a different path connecting $x$ to $y$ along which $S$ could be more readily computed.$)$

a$)1\mathrm{.}70$

b$)1\mathrm{.}50$

c$)1\mathrm{.}37$

d$)1\mathrm{.}25$

e$)0\mathrm{.}916$