For which element are the number of protons, electron, and neutrons are 36, 36, and 48 respectively? a cadmium b rubidium c bromine d krypton

Krypton has 36 protons and electrons and 48 neutrons. 

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.