A reaction that requires energy input to proceed is described as

• A. Spontaneous
• B. Non-Spontaneous
• C. Activation Energy
• D. Oxidation

Answer: (B)

The idea being tested is spontaneity and energy changes in a reaction. A reaction that proceeds on its own is considered spontaneous because it results in a net drop in free energy (the overall process is energetically favorable). If a reaction requires continual energy input to move forward, it is non-spontaneous under those conditions, meaning the overall free energy change is not favorable and energy must be supplied to drive it. Activation energy is just the energy barrier to start a reaction; it doesn’t by itself determine whether the reaction is spontaneous or not, since a reaction can have a large barrier yet be spontaneous if the overall energy change is negative. Oxidation describes a type of redox process, not the spontaneity of the reaction. So a reaction that needs energy input to proceed is described as non-spontaneous.