When the free-energy change (ag) of a reaction is negative, the reaction is said to be: endergonic non spontaneous spontaneous endothermic

Spontaneous

Explanation:

For a spontaneous reaction , the value for the change in free energy or gibbs' free energy is negative .

The change in free energy , i.e. , ΔG , denotes the maximum amount of usable energy released , as going from initial state , i.e. , the reactant towards the final state , i.e. , the product .

And , the sign of the  ΔG , determines whether the reaction is Spontaneous or non Spontaneous or at equilibrium ,

i.e. ,

if

ΔG < 0 , the reaction is Spontaneous

ΔG > 0 , the reaction is non Spontaneous

ΔG = 0 , the reaction is at equilibrium

For ,

ΔG < 0 , that the reaction proceed without any energy input , hence , it is  Spontaneous in nature .

aquifers are bounded above and below by impermeable rock. the driving force of groundwater movement in confined aquifers is pressure, rather than gravity.