What does (I) means in a chemical equation

Spontaneity tell us the direction of the reaction, but not how fast it goes. gibbs free energy brings together enthalpy, entropy and temperature in one easy formula. g = h - ts. and, finally the sign of delta g is always negative for a spontaneous reaction.

False, as a substance changes from a solid to a liquid and from a liquid to a gas the molecules get farther apart from each other