I was studying 2nd law thermodynamics. In that context found the clausius's inequality saying closed integral of dQ/T <0 for irreversible process. And from the reversible process entropy was defined. And from that view they said that for irreversible process dS>dQ/T. Now when I saw some examples of calcutating entropy for irreversible process, they connected two states by a reversible path and calculated entropy change because entropy is a state function . My question is at one side clausius inequality is saying that for irreversible process dS>dQ/T and at other hand they are calculating entropy change in irreversible process by dS=dQ/T. Isn't it contradictory ? Sorry for my bad english and as I am posting from mobile I can't able to use latex for mathematics so apolozise for that . Thanx in advance.