True or false. the only elements that can be used as fuel in a nuclear power plant are those in which a chain reaction can occur.

False. a  lot of elements are used in nuclear power which does not have chain reactions. 

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.