Considering the relationship
TdS = dU + PdV between the entropy (S), internal energy (U), pressure (P), temperature (T) and volume (V),
Which of the following statements is correct?
(a) It is applicable only for a reversible process
(b) For an irreversible process, tdS>dU+PdV
(c) It is valid only for an ideal gas
(d) It is equivalent to first law, for a eversible process