Is it ensure, insure, or assure?
Any of a group of unsaturated hydrocarbons that havee carbon atoms in chains linked by one or more triple bonds and that have the general formula CnH2n-2. Alkynes can be solid, liquid, or gaseous and include acetylene. ◇ The group of alkynes as a whole is called the alkyne series or the acetylene series. The first five members of the alkyne series are acetylene (or ethyne), propyne, butyne, pentyne, and hexyne.