Define entropy and entropy change. What are the units of entropy?

What is the physical significance of entropy?

Account for the following:
(i) Why does real crystal have more entropy than an ideal crystal?

(ii) Why the entropy of a pure substance is taken as zero at absolute zero?

(iii) Why the entropy of the universe is continuously increasing?

Which of the following reaction will have a greater change in entropy? Explain.

Predict the change in entropy for the system in which the following physical changes occur:
(i) Dissolving cream in a cup of coffee.
(ii) The beating of an egg for an omellete.
(iii) The formation of a rain drop in a cloud.
(iv) The crystallization of a metal alloy from the molten state.

In the following changes, state whether order has increased or decreased and consequently the direction of change of entropy of the system:

In the following changes, state whether order has increased or decreased and consequently by the direction of change of entropy of the system:

Will entropy increased or decrease during boiling of an egg? Comment on the statement.

The entropy of steam is more than that of water at its boiling point. Explain.

For an isolated system, ∆U = 0, what will be ∆S ?