Answer: four , double
Step-by-step explanation:
Saturated hydrocarbons are defined as the hydrocarbons in which a single bond is present between carbon and carbon atoms. The general formula for these hydrocarbons is
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Unsaturated hydrocarbons are defined as the hydrocarbons which have double or triple covalent C-C bonds. They are known as alkenes and alkynes respectively. The general formula for these hydrocarbons is
and
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Butene is
has molecular formula of
and thus has four carbon atoms and one double bond or pi bond.