Simply by observing the existence of the Cherenkov radiation from a particle, one can determine its relative velocity with respect to the light speed in medium. Knowing that, one can determine the particle momentum.
It is a ring formed carbon skeleton. The smallest possible cyclic hydrocarbon is cyclopropane (triangular C3H6) together with cyclobutane both being rather unstable (degration to linear propene and 1-butene). Five and six membered rings are quite common.
Definition - What does Unsaturated Hydrocarbon mean? Unsaturated Hydrocarbon is a hydrocarbon that has double or triple covalent bonds between adjoining carbon atoms. These bonds make unsaturated hydrocarbons more reactive than the saturated hydrocarbons. They have fewer hydrogen atoms bonded to carbon atoms as compared to saturated hydrocarbons. Hydrocarbons having at least one triple bond are known as alkynes and those having, at least, one double bond are known as alkenes.