Question

which term describes this reaction? addition condensation elimination substitution

Explanation:

In an addition reaction, two or more molecules combine to form a larger molecule. Here, ethene ($C_2H_4$) and chlorine ($Cl_2$) combine to form 1,2 - dichloroethane ($C_2H_4Cl_2$). The double - bond in ethene is broken and the chlorine atoms are added across it. Condensation reactions involve the loss of a small molecule like water. Elimination reactions result in the formation of a double - bond or triple - bond by the removal of atoms or groups. Substitution reactions involve one atom or group being replaced by another.

Answer:

A. addition