Question

Match the columns

Column I		Column II
A	$p_{ext}=0$	p	Free expansion of an ideal gas
B	$q=p_{ext}\left(V_f-V_i\right)$	q	Adiabatic change
C	$q=2.303nRT\log \left(V_f/V_i\right)$	r	Isothermal reversible change
D	$\Delta U=W_{ad}$	s	Isothermal irreversible change

• A. A - (p), B - (s), C - (r), D - (q)
• B. A - (p), B - (q), C - (r), D - (s)
• C. A - (p), B - (r), C - (s), D - (q)
• D. A - (p), B - (r), C - (q), D - (s)

Answer 1

Answer: (A)

$A-(p),B-(s),C-(r),D-(q)$
Expansion of a gas in vacuum $\left(p_{ext}=0\right)$ is called free expansion.
For isothermal irreversible change
$q=-W=p_{ext}\left(V_f-V_i\right)$
for isothermal reversible change
$q=-W=nRT\ln \left(V_f/V_i\right)$
$=2.303nRT\log V_f/V_i$
For adiabatic change, $q=0,\Delta U=W_{ad}$