Although dissolution of ammonium chloride in water is endothermic yet it dissolves. Why?

What is the standard state of the substance?

What are exothermic and endothermic compounds?

What is the physical significance of entropy?

What is the sign of ∆S for a spontaneous process in an isolated system?

Predic the sign of  for:

Give the relation between entropy change and heat exchanged between the sytem and surrounding for a reversible reaction taking place at temperature T.

Give a statement which includes the main ideas of the first and second laws of thermodyanimcs.

Define standard entropy (S⁰).

State the effect of increased temperature on the entropy of the substance.