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.
an organic compound that contains a hydrocarbon ring. Saturated and unsaturated straight-chain and branched-chain hydrocarbons are not the only types of hydrocarbons. In some hydrocarbon compounds, the carbon chain is in the form of a ring. Figure 20.10 shows the structures of some of these hydrocarbons.