The hydrocarbon in which all the four valencies of carbon are fully occupied is called

Alkanes have all four carbon bonds filled with single bonds. Each carbon connects to four other atoms. This makes them saturated hydrocarbons.

Alkenes have double bonds. Alkynes have triple bonds. Both have unfilled valencies. Cycloalkanes are saturated but form rings.

Remember: Alkanes end in -ane. They follow the formula CₙH₂ₙ₊₂.