3.3.2 Alkanes

Which statement is correct about the fractional distillation of crude oil?

• A zeolite catalyst is used.

• Each fraction contains a mixture of hydrocarbons.

• Gaseous fractions are formed by breaking covalent bonds.

• The fractionating column is hottest at the top.

The table shows possible conditions and products for the cracking of alkanes. Which row is correct?

• A

• B

• C

• D

Which catalyst is used in the catalytic cracking of alkanes?

• Concentrated phosphoric acid

• Iron

• Nickel

• Zeolite

Tetradecane (C₁₄H₃₀) is an alkane found in crude oil. When tetradecane is heated to a high temperature, one molecule of tetradecane decomposes to form one molecule of hexane and three more molecules.

Which of the following could represent this reaction?

• C₁₄H₃₀ → C₆H₁₄ + C₄H₈ + 2C₂H₄

• C₁₄H₃₀ → C₆H₁₄ + C₆H₁₂ + C₂H₄

• C₁₄H₃₀ → C₅H₁₂ + 3C₃H₆

• C₁₄H₃₀ → C₆H₁₄ + C₂H₆ + 2C₃H₆

Which correctly represents an incomplete combustion of pentane?

• C₅H₁₂ + 8O₂ ⟶ 5CO₂ + 6H₂O

• C₅H₁₂ + 8O₂ ⟶ 4CO + CO₂ + 6H₂O

• C₅H₁₂ + 6O₂ ⟶ 4CO + CO₂ + 6H₂O

• C₅H₁₂ + 5O₂ ⟶ 4CO + CO₂ + 4H₂O + 2H₂

Which of these substances does not contribute to the greenhouse effect?

• Unburned hydrocarbons.

• Carbon dioxide.

• Water vapour.

• Nitrogen.

Sulfur dioxide (SO₂) is produced when some fossil fuels are burned.

Which of the following statements is true?

• Sulfur dioxide can be removed from waste gases in a power station by an acid-base reaction with calcium oxide

• Sulfur dioxide is insoluble in water.

• Sulfur dioxide is a basic oxide.

• Sulfur dioxide is an ionic compound.

Which equation represents a termination step?

• 
• 
• 
• 

Which equation is a propagation step in the conversion of trichloromethane into tetrachloromethane by reaction with chlorine in the presence of ultraviolet light?

• CHCl₃ + Cl₂ ⟶ CCl₄ + HCl

• ●CCl₃ + ●Cl ⟶ CCl₄

• CHCl₃ + ●Cl ⟶ CCl₄ + ●H

• ●CCl₃ + Cl₂ ⟶ CCl₄ + ●Cl

Which of the following mechanisms does not occur in reactions of bromoethane?

• Electrophilic addition

• Elimination

• Nucleophilic substitution

• Radical substitution