Question

Select the correct statements.
a. There is asymmetry between converting work to heat and converting heat to work.
b. No process is possible in which the sole result is the absorption of heat from a reservoir and its complete conversion into work.
c. For every chemical reaction at equilibrium, standard change in Gibbs free energy is zero.
d. At constant temperature and pressure, chemical reactions are spontaneous in the direction of decreasing Gibbs energy.

• A. Statement a
• B. Statement b
• C. Statement c
• D. Statement d

Answer 1

Answer: (A), (B), (D)

The correct options are
A Statement b
B Statement a
D Statement d

a is correct as work can be converted to heat without any other effects on the system but the opposite is not true as it violates the 2nd law of thermodynamics.

Also, $\Delta G=-ve$ for spontaneous process and zero for reactions which are at thermodynamic equilibrium. However, $\Delta G^{\ominus }\ne 0$ at equilibrium.

Statement (b) represents the Carnot theorem. It is the consequence of the 2nd law of thermodynamics.

Hence, A,B and D are correct options