Year 12 Organic Quiz (intervention)

What is the name of this compound?

• ethanol

• ethanal

• ethanone

• methanal

Answer explanation

The compound is ethanal, which is an aldehyde with the formula C2H4O. Ethanol is an alcohol, ethanone is a ketone, and methanal is formaldehyde. Thus, the correct name for this compound is ethanal.

What is the name of this compound?

• propan-2-al

• propanane

• propanone

• propanal

Answer explanation

The compound is propanone, commonly known as acetone, which is a ketone. It has the structure CH3COCH3, distinguishing it from the other options like propanal (an aldehyde) and propan-2-al (an alcohol).

Which compound is a structural isomer of Z-but-2-ene?

• butane

• E-but-2-ene

• cyclobutane

• methylbut-2-ene

Answer explanation

Cyclobutane is a structural isomer of Z-but-2-ene because it has the same molecular formula (C4H8) but a different connectivity of atoms, forming a ring structure, unlike the linear or branched forms of the other options.

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

Answer explanation

The correct choice, ●CCl₃ + Cl₂ ⟶ CCl₄ + ●Cl, represents a propagation step where the chlorine radical reacts with trichloromethane to form tetrachloromethane and regenerate a chlorine radical, continuing the reaction.

How many structural isomers are there with the molecular formula C₃H₆BrCl?

• 4

• 5

• 6

• 7

Answer explanation

The molecular formula C3H6BrCl can form 5 structural isomers by varying the positions of the Br and Cl atoms and the arrangement of carbon atoms. Thus, the correct answer is 5.

An organic compound is found to contain 40.0% carbon, 6.7% hydrogen and 53.3% oxygen.Which of the following compounds could this be?

• Ethanol

• Ethanoic acid

• Methanol

• Methanoic acid

Answer explanation

To determine the compound, we calculate the molar ratios from the percentages. Ethanoic acid (C2H4O2) matches the given composition of 40% C, 6.7% H, and 53.3% O, while the other options do not fit these ratios.

Which one of the following mechanisms is not involved in the reaction sequence below?

CH₃CH₃ → CH₃CH₂Cl → CH₃CH₂OH → CH₂=CH₂ → CH₃CH₂Br

• electrophilic addition

• electrophilic substitution

• nucleophilic substitution

• free-radical substitution

Answer explanation

The reaction sequence involves nucleophilic substitution (CH3CH2Cl to CH3CH2OH), free-radical substitution (CH3CH3 to CH3CH2Cl), and electrophilic addition (to form CH2=CH2). Electrophilic substitution is not involved.

What is the correct systematic name for

• 2-bromo-3-methylpent-2-ene

• 2-bromo-3-ethylbut-2-ene

• 3-bromo-2-ethylbut-2-ene

• 4-bromo-3-methylpent-3-ene

Answer explanation

The correct systematic name is 2-bromo-3-methylpent-2-ene, as it accurately describes the structure with a bromine at the second carbon and a methyl group at the third carbon of a pentene with a double bond at the second position.

Which diagram gives the skeletal formula of

2-chloropentan-3-ol ?

• A

• B

• C

• D

Answer explanation

The skeletal formula for 2-chloropentan-3-ol shows a five-carbon chain with a hydroxyl (-OH) group on the third carbon and a chlorine (Cl) atom on the second carbon. Diagram A accurately represents this structure.

Which reaction is not an electrophilic addition ?

• A

• B

• C

• D

Answer explanation

Electrophilic addition involves the attack of an electrophile on a nucleophile. Choice D does not fit this mechanism, making it the correct answer as it represents a different type of reaction.