Question

The change in entropy for the following transformations is respectively
(i) $S{O}_{2}C{1}_2\left(g\right)\stackrel{\Delta }{\to }S{O}_2\left(g\right)+C{1}_2\left(g\right)$
(ii) $nC{H}_2=C{H}_2\stackrel{Catalyst}{\to }[-C{H}_2-C{H}_2-{]}_{n\left(s\right)}$
(iii) $I_2\left(s\right)\underset{1atm}{\overset{\Delta }{\to }}{I}_2\left(v\right)$
(iv) Adiabatic reversible expansion of an ideal gas

• A. +,-,0,+
• B. +,-,0,0
• C. -,+,+,0
• D. +,-,+,0

Answer 1

The correct option is D +,-,+,0

(i) randomness increases
(ii) randomness decreases
(iii) randomness increases
(iv) no change of heat
$\Delta S=\frac{dq}{T}$
$[\because dq=0]$
$\Delta S=0$