Final answer:
The entropy of an isolated system never decreases, which is a key qualitative statement of the second law of thermodynamics reflecting the irreversibility of spontaneous processes and the directional nature of heat transfer.
Step-by-step explanation:
What are some qualitative statements regarding the second law of thermodynamics? The second law of thermodynamics provides insight into the directional flow of thermal energy and entropy changes within a system.
A qualitative statement that accurately reflects this law is: 'The entropy of an isolated system never decreases.' This law implies that entropy either increases or remains constant in any spontaneous process, and heat energy will spontaneously transfer from a higher temperature body to a lower temperature body but never the reverse without external work.
When addressing the question's choices, we can assess that:
- (a) Energy is conserved in all processes - This pertains more to the first law of thermodynamics, which focuses on the conservation of energy.
- (b) Entropy of an isolated system never decreases - This is a correct representation of the second law of thermodynamics.
- (c) Work done is always reversible - This statement is not accurate as per the second law; many processes are irreversible due to entropy increase.
- (d) Heat transfer occurs only in solids - This statement is incorrect as heat transfer can occur in solids, liquids, and gases.
Therefore, the correct qualitative statement regarding the second law of thermodynamics from the given options is 'entropy of an isolated system never decreases'.