Organic Chemistry Quiz

Match each organic process with its correct description: Column I (Hydrogenation) Column II (Description) A. Esterification 1 Formation of alcohol from alkene B. Hydration 2 Addition of water across a C=C C. Hydrogenation 3 Conversion of carboxylic acid + alcohol → ester D. Combustion 4 Complete oxidation by burning in O2

1. A-3, B-2, C-1, D-4
2. A-2, B-3, C-4, D-1
3. A-3, B-1, C-2, D-4
4. A-2, B-4, C-1, D-3

Answer: (a) A-3, B-2, C-1, D-4

Hexane has several structural isomers. Which of the following isomers has the highest boiling point?

1. 2-Methylpentane
2. n-Hexane
3. 2,2-Dimethylbutane
4. 3-Methylpentane

Answer: (b) n-Hexane

A student adds bromine water to an unknown organic compound, and the solution decolourises immediately. What can be inferred about the compound?

1. It is a saturated hydrocarbon.
2. It is an alcohol.
3. It is a carboxylic acid.
4. It is an alkene or alkyne.

Answer: (d) It is an alkene or alkyne.

Which of the following factors increases the boiling point of an organic compound? 1. Presence of hydrogen bonding 2. Longer carbon chains 3. Higher molecular mass 4. Non-polarity of the molecule

1. 1, 2, 3 and 4
2. 1 and 2
3. 1, 2, and 4
4. 1, 2, and 3

Answer: (d) 1, 2, and 3

Carboxylic acids react with alcohols in the presence of concentrated sulphuric acid to produce esters. Esters are used in perfumes and flavourings due to their pleasant smell. What is the role of sulphuric acid in this reaction?

1. It provides water for esterification.
2. It increases the volatility of the ester.
3. It acts as a catalyst by lowering the activation energy.
4. It reacts with the carboxylic acid to form an intermediate.

Answer: (c) It acts as a catalyst by lowering the activation energy.

Two organic compounds, shown below, exhibit significant differences in their physical and chemical properties. Which of the following factors is primarily responsible for these differences?

1. The difference in their functional groups
2. The difference in their molecular masses
3. The difference in their number of carbon atoms
4. The difference in their number of hydrogen atoms

Answer: (a) The difference in their functional groups

Two alkanes are compared: one is a straight-chain alkane, and the other is a branched alkane with a symmetrical structure. Branching affects the physical properties of alkanes due to changes in molecular interactions. Which of the following correctly describes the effect of branching on their boiling and melting points?

1. Raises the boiling point; raises the melting point.
2. Lowers the boiling point; raises the melting point.
3. Raises the boiling point; lowers the melting point.
4. Lowers the boiling point; lowers the melting point.

Answer: (b) Lowers the boiling point; raises the melting point.

Which of the following statements about nucleophiles is/are correct? 1. A nucleophile is an electron pair donor. 2. Hydroxide ion (OH⁻) acts as a nucleophile in the hydrolysis of haloalkanes. 3. Ammonia (NH₃) is not a nucleophile because it does not have a negative charge. 4. A nucleophile must always contain a lone pair of electrons.

1. 1 and 2 only
2. 3 and 4 only
3. 1, 2, and 4 only
4. 1, 2, 3, and 4

Answer: (c) 1, 2, and 4 only

During a practical experiment, a student isolates an isobutyl group from a larger molecule. Based on the structure of this group (shown in the diagram below), how would you classify it?

1. Quaternary
2. Tertiary
3. Secondary
4. Primary

Answer: (d) Primary

The reaction mechanism for saponification involves several steps. Identify the correct sequence: 1. Neutralisation of fatty acids to form soap 2. Hydrolysis of triglycerides into fatty acids and glycerol 3. Combination of glycerol with water Choose the correct order.

1. 2 → 1 → 3
2. 1 → 2 → 3
3. 1 → 3 → 2
4. 3 → 1 → 2

Answer: (a) 2 → 1 → 3