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	$q =2.303 nRT \log \left( V _{ f } / V _{ i }\right)$	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
$q=-W=p_{e x t}\left(V_f-V_i\right)$
for isothermal reversible change
$q=-W=n R T \ln \left(V_f / V_i\right)$
$=2.303\, n R T \log V_f / V_i$
For adiabatic change, $q=0, \Delta U=W_{a d}$