21. The term “saturation” in hydrocarbons refers to:

a) The presence of double bonds
b) The presence of triple bonds
c) The presence of single bonds only
d) The absence of rings
Answer: c) The presence of single bonds only

22. The most stable conformation of butane is:

a) Staggered
b) Eclipsed
c) Linear
d) Cyclic
Answer: a) Staggered

23. The process used to separate alkanes from a mixture is:

a) Distillation
b) Cracking
c) Hydrogenation
d) Dehydration
Answer: a) Distillation

24. The major product of the incomplete combustion of alkanes is:

a) Carbon dioxide
b) Water
c) Carbon monoxide
d) Oxygen
Answer: c) Carbon monoxide

25. The characteristic reaction of alkynes is:

a) Addition reaction
b) Substitution reaction
c) Elimination reaction
d) Polymerization
Answer: a) Addition reaction

26. The term “isomerism” in aliphatic hydrocarbons refers to:

a) Compounds with different molecular formulas
b) Compounds with the same molecular formula but different structures
c) Compounds with the same boiling points
d) Compounds with the same melting points
Answer: b) Compounds with the same molecular formula but different structures

27. The formula for cyclohexane is:

a) C₄H₁₀
b) C₆H₁₂
c) C₈H₁₆
d) C₄H₈
Answer: b) C₆H₁₂

28. The reaction between an alkene and water in the presence of an acid catalyst is known as:

a) Hydration
b) Hydrogenation
c) Dehydrogenation
d) Halogenation
Answer: a) Hydration

29. The presence of a double bond in an alkene affects its:

a) Boiling point
b) Melting point
c) Density
d) Refractive index
Answer: a) Boiling point

30. The simplest member of the alkane series is:

a) Ethane
b) Methane
c) Propane
d) Butane
Answer: b) Methane