Benzene is a very stable molecule. This stability is due to the delocalization of π electrons whereas no such delocalization of π electrons is possible in ethene. In ethene, the π electronic cloud is present above and below the plane of atoms and is more exposed to electrophile attack.
We measure the voltage between two points but why? what is the reason behind it? If you don’t know then don’t worry because today we are doing to discuss that Why Voltages Are Measured Between Two Points?