Hydrocarbons Chapter-Wise Test 8

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which hydrocarbon with 7 carbon atoms has the lowest boiling point among its isomers?

For \( \ce{C7H16} \), 2,2,3-trimethylbutane, with its highly branched structure, has the lowest boiling point due to minimal surface area.

Heptane
2,2,3-Trimethylbutane
3-Methylhexane
2,3-Dimethylpentane
2

Which hydrocarbon with 8 carbon atoms has the most branched structure among its isomers?

For \( \ce{C8H18} \), 2,2,3,3-tetramethylbutane has four methyl branches, the most compact and branched structure among octane isomers.

Octane
2-Methylheptane
2,2-Dimethylhexane
2,2,3,3-Tetramethylbutane
4

What is the common name of \( \ce{CH3CH2CH2CH2CH3} \)?

The compound \( \ce{CH3CH2CH2CH2CH3} \) is a five-carbon alkane, commonly known as pentane.

Butane
Pentane
Hexane
Propane
2

Which hydrocarbon with molecular formula \( \ce{C7H14} \) has a six-membered ring and one double bond?

Cyclohexene (\( \ce{C6H10} \)) with a methyl group becomes methylcyclohexene (\( \ce{C7H14} \)), a six-membered ring with one double bond.

Cycloheptane
Heptene
Methylcyclohexene
Cyclohexane
3

Which hydrocarbon class has a planar structure due to delocalized π electrons?

Aromatic hydrocarbons, like benzene, have a planar ring structure with delocalized π electrons, contributing to their stability.

Aromatics
Alkanes
Alkenes
Cycloalkanes
1

What is the IUPAC name of \( \ce{CH3CH2CH2CH(CH3)2} \)?

The longest chain has 5 carbons (pentane), with two methyl groups on the fourth carbon, making it 2,2-dimethylpentane.

3-Methylpentane
2,2-Dimethylpentane
Hexane
2-Methylpentane
2

A hydrocarbon with 8 carbon atoms has two ethyl branches. What is its IUPAC name?

For \( \ce{C8H18} \), a 4-carbon chain (butane) with ethyl groups on carbons 2 and 3 is 2,3-diethylbutane.

2,2-Diethylhexane
2,3-Diethylbutane
3-Ethylheptane
2,2,3-Trimethylpentane
2

Which substituent on a benzene ring directs electrophiles to both ortho and para positions?

The \( -\ce{CH3} \) group donates electrons via hyperconjugation, directing electrophiles to ortho and para positions.

\( -\ce{NO2} \)
\( \ce{-CH3} \)
\( -\ce{CN} \)
\( -\ce{COOR} \)
2

Which hydrocarbon with 6 carbon atoms has the lowest boiling point among its isomers?

For \( \ce{C6H14} \), 2,2-dimethylbutane, with its compact branched structure, has the lowest boiling point due to reduced surface area.

Hexane
2,2-Dimethylbutane
2-Methylpentane
3-Methylpentane
2

Which hydrocarbon with molecular formula \( \ce{C9H16} \) has a cyclic structure with one degree of unsaturation?

Cyclononene (\( \ce{C9H16} \)) is a nine-membered ring with one double bond, giving one degree of unsaturation.

Cyclononane
Nonane
Nonadiyne
Cyclononene
4

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