What is meant by absolute entropy?

Mixing of non-reacting gases is generally accompanied by

What is entropy?

The value of entropy of the universe is

Direct conversion of $A$ to $B$ is difficult,so it is carried out by the path shown below. If $e.u.$ is the entropy unit,what will be $\Delta S_{(A \rightarrow B)}$?
Given:
$\Delta S_{(A \rightarrow C)} = 50 \ e.u.$
$\Delta S_{(C \rightarrow D)} = 30 \ e.u.$
$\Delta S_{(B \rightarrow D)} = 20 \ e.u.$

In which of the following reactions,standard reaction entropy change $(\Delta S^o)$ is positive and standard Gibb's energy change $(\Delta G^o)$ decreases sharply with increasing temperature?