Alkanes are ❌ hydrocarbons. This means that their ❌ atoms are joined to each other by ❌ bonds. This makes them relatively ❌, apart from their reaction with ❌ in the air - which we call burning or ❌.

Alkenes contain a carbon-❌ double bond. This bond is why the alkenes are ❌ reactive than the alkanes. The number of ❌ atoms in an alkene is ❌ the number of carbon atoms, so they have the general formula Equation C❌H❌.

Alcohols all contain the ❌ functional group –❌, which is responsible for the ❌ of alcohols.
The names of alcohols end ‘-❌’, eg ethanol.
The first three alcohols in the series are methanol, ethanol and ❌. They are highly flammable, making them useful as fuels. They are also used as ❌ in marker pens, medicines, and cosmetics (such as deodorants and perfumes). Ethanol is mixed with ❌ for use as a fuel.