N5 Chemistry Homologous Series MC 2015-2019 & 2022-2023

The name of the above compound is

• 2,3-dimethylpropane

• 3,4-dimethylpropane

• 2,3-dimethylpentane

• 3,4-dimethylpentane

Answer explanation

Carbon 1 is closest to the first branch.

The shortened structural formula for an organic compound is

CH₃CH(CH₃)CH(OH)C(CH₃)₃

Which of the following is another way of representing this structure?

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Three members of the cycloalkene homologous series are shown. Which of the following is the general formula for this homologous series?

• C_nH_2n—4

• C_nH_2n+2

• C_nH_2n

• C_nH_2n—2

Which of the following compounds belongs to the same homologous series as the compound

with the molecular formula C₃H₈?

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Answer explanation

both C₃H₈ and C₅H₁₂ fit the general formula C_nH_2n+2

The systematic name for the structure shown is

• 1,2-dimethylpent-1-ene

• 2,3-dimethylpent-1-ene

• 3,4-dimethylpent-4-ene

• 3,4-dimethylpent-1-ene

Two isomers of butene are: Which of the following structures represents a third isomer of butene?

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Which of the following could be the molecular formula for an alkane?

• C₇H₁₆

• C₇H₁₄

• C₇H₁₂

• C₇H₁₀

Answer explanation

A C₇H₁₆ gives a general formula of C_nH_2n+2. Alkanes have general formula C_nH_2n+2.

B C₇H₁₄ gives a general formula of C_nH_2n. Alkanes have general formula C_nH_2n+2.

C C₇H₁₂ gives a general formula of C_nH_2n-2. Alkanes have general formula C_nH_2n+2.

D C₇H₁₀ gives a general formula of C_nH_2n-4. Alkanes have general formula C_nH_2n+2.

Identify which of the following is an isomer of

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Answer explanation

C₆H₁₄ structure drawn is 2-methylpentane

A Cyclohexane C₆H₁₂ has different formula so cannot be an isomer of C₆H₁₄.

B 2-methylpentane again but drawn different so cannot be an isomer.

C 3-methylpentane C₆H₁₄ so same formula but different structure so is an isomer.

D 2-methylbutane C₅H₁₂ has different formula so cannot be an isomer of C₆H₁₄.

The structure of 2-methylbut-2-ene is shown. Which of the following represents an isomer of 2-methylbut-2-ene?

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Which of the following would not be produced by an addition reaction of but-2-ene?

• CH₃CH₂CH₂CH₃

• CH₃CH₂CH₂CH₂OH

• CH₃CH(OH)CH₂CH₃

• CH₃CHBrCHBrCH₃