Hydrocarbons Chapter-Wise Test 17

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which hydrocarbon produces 5 moles of \( \ce{CO2} \) and 6 moles of \( \ce{H2O} \) per mole upon complete combustion?

For \( \ce{C5H12} \) (pentane): \( \ce{C5H12 + 8O2 -> 5CO2 + 6H2O} \), producing 5 \( \ce{CO2} \) and 6 \( \ce{H2O} \).

\( \ce{C5H12} \)
\( \ce{C6H14} \)
\( \ce{C4H10} \)
\( \ce{C5H10} \)
1

Which type of hydrocarbon contains carbon-carbon triple bonds?

Alkynes are unsaturated hydrocarbons characterized by at least one carbon-carbon triple bond.

Alkynes
Alkanes
Alkenes
Aromatics
1

Which hydrocarbon is used as a fuel in jet engines?

Kerosene, a mixture of hydrocarbons including undecane (\( \ce{C11H24} \)), is used as jet fuel.

Undecane
Methane
Ethene
Benzene
1

Which substituent on a benzene ring moderately activates it and directs electrophiles to ortho and para positions?

The \( -\ce{CH2CH3} \) (ethyl) group activates the ring via hyperconjugation and directs electrophiles to ortho and para positions.

\( -\ce{NO2} \)
\( -\ce{CH2CH3} \)
\( -\ce{COOH} \)
\( -\ce{Cl} \)
2

What is the effect of branching on the density of alkanes?

Branching in alkanes reduces the surface area, lowering intermolecular forces and thus decreasing density.

Increases
No effect
Fluctuates
Decreases
4

What type of reaction does benzene primarily undergo?

Despite its unsaturation, benzene undergoes electrophilic substitution reactions due to its stable aromatic structure.

Addition
Combustion
Electrophilic substitution
Nucleophilic substitution
3

Which hydrocarbon produces the highest number of \( \ce{CO2} \) molecules per mole upon complete combustion among the following?

Octane (\( \ce{C8H18} \)) produces 8 moles of \( \ce{CO2} \) per mole, the highest among the options.

\( \ce{C6H14} \)
\( \ce{C5H12} \)
\( \ce{C8H18} \)
\( \ce{C7H16} \)
3

Which hydrocarbon with 7 carbon atoms has the maximum number of sigma bonds?

Heptane (\( \ce{C7H16} \)) has 20 sigma bonds (6 \( \ce{C-C} \), 14 \( \ce{C-H} \)), the maximum for 7 carbons, as it is saturated.

Heptene
Cycloheptene
Toluene
Heptane
4

Which hydrocarbon with 5 carbon atoms has the highest boiling point?

Pentane (\( \ce{C5H12} \)), with a straight chain, has the highest boiling point among \( \ce{C5} \) hydrocarbons due to greater surface area.

Pentene
Cyclopentane
Pentane
2-Methylbutane
3

Which hydrocarbon with molecular formula \( \ce{C7H12} \) contains two triple bonds?

Heptadiyne (\( \ce{CH#C-CH2-C#C-CH2-CH3} \)) has two triple bonds, giving four degrees of unsaturation, fitting \( \ce{C7H12} \).

Heptene
Heptadiyne
Cycloheptene
Toluene
2

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