What type of bond is present in ethylene (C2H4)?

In ethylene (C2H4), the correct type of bond is a double bond. This is because ethylene consists of two carbon atoms that are connected to each other by a double bond, along with each carbon being bonded to two hydrogen atoms.

The double bond between the carbon atoms is comprised of one sigma bond and one pi bond. The sigma bond is formed by the head-on overlap of the atomic orbitals of the carbon atoms, while the pi bond results from the side-to-side overlap of the remaining unhybridized p orbitals on each carbon atom. This arrangement allows ethylene to have a planar structure and gives it characteristic reactivity compared to alkanes, which contain only single bonds and therefore are saturated hydrocarbons.

Given the options, a single bond would not account for the structural makeup of ethylene, and a triple bond or quadruple bond does not exist in this molecule either, as that would require a different arrangement of atoms. Thus, identifying ethylene as containing a double bond is essential to understanding its structure and reactivity in organic chemistry.