Question

In an isothermal reversible compression of an ideal gas the signs of

	$q$	$\Delta S$	$w$
(a)	+	-	-
(b)	-	+	-
(c)	+	-	+
(d)	-	-	+

• A. a
• B. b
• C. c
• D. d

Answer 1

Answer: (D)

For isothermal reversible compression, work done $(w)$ is $+ve$
As $q=-w$ therefore $q$ is $-ve$
Also, $\Delta s=\frac{q_{iso,rev}}{T}$
As $q$ is $-Ve$ so, $\Delta S$ will also be $-ve$