A system changes from state $$X$$ to $$Y$$ with a change in internal energy measuring to $$25\,kJ\,mo{l^{ - 1}},$$ by a reversible path and returns from $$Y$$ to $$X$$ by an irreversible path. What will be the net change in internal energy ?
A.
$$25\,kJ$$
B.
$$ > 25\,kJ$$
C.
$$ < 25\,kJ$$
D.
$${\text{Zero}}$$
Answer :
$${\text{Zero}}$$
Solution :
For a cyclic process, net change in internal energy is zero. Change in internal energy does not depend on the path by which final stage is reached.
Releted MCQ Question on Physical Chemistry >> Chemical Thermodynamics
Releted Question 1
The difference between heats of reaction at constant pressure and constant volume for the reaction : $$2{C_6}{H_6}\left( l \right) + 15{O_{2\left( g \right)}} \to $$ $$12C{O_2}\left( g \right) + 6{H_2}O\left( l \right)$$ at $${25^ \circ }C$$ in $$kJ$$ is
$${\text{The}}\,\Delta H_f^0\,{\text{for}}\,C{O_2}\left( g \right),\,CO\left( g \right)\,$$ and $${H_2}O\left( g \right)$$ are $$-393.5,$$ $$-110.5$$ and $$ - 241.8\,kJ\,mo{l^{ - 1}}$$ respectively. The standard enthalpy change ( in $$kJ$$ ) for the reaction $$C{O_2}\left( g \right) + {H_2}\left( g \right) \to CO\left( g \right) + {H_2}O\left( g \right)\,{\text{is}}$$