Why is a 9-v transistor battery used as the source of electrical power for electrolysis rather than the power supply that plugs into the wall electrical current?

The 9-v transistor battery is a direct current source, while the power supply from the wall socket is an alternating current source.

Explanation:

A direct current (DC) is one that flows continuously without any minimum and maximum values. This is majorly obtained from generators, batteries or cells etc.

An alternating current (AC) is a type that flows in a sinusoidal manner, having minimum and maximum value with respect to its flowing frequency. An example is the one obtained from the wall electrical source , generators etc.

An alternating current is not mainly used for electrolysis because of its nature. It would cause a switch of the electrodes in every cycle. Therefore, a direct current source is used.

The 9-v transistor battery is a direct current source, while the power supply from the wall is an alternating current source.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.