Answer:
(3) carbon atoms
Step-by-step explanation:
2- butanol is a secondary alcohol containing C,H and O with a molecular formula: C4H10O and a structural formula: CH3CH2CH(OH)CH3
2- butene is an unsaturated hydrocarbon i.e. an alkene containing C and H only with a molecular formula: C4H8 and a structural formula:
CH3CH2CH=CH2
Based on the given options, the only common ground between 2-butanol and 2-butene is that both contain carbon atoms.