Why do the noble gases not form compounds readily?

Because they have a full outer electron shell they are quite happy staying on their own rather than bonding to other elements, this is why they are also known as inert gases.

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.

The correct answer is "hydrogen".