Organic Molecules is one of 10 topics in the Grade 12 Physical Sciences CAPS syllabus, covered across 4 lessons on Study Vault. Below are real practice questions from this topic with full worked answers.
Sample practice questions
Easy
1. What is a functional group?
The atom or group of atoms responsible for the characteristic chemical properties of a compound
Any carbon atom in a chain
The longest chain of carbon atoms in a molecule
A compound containing only carbon and hydrogen
Answer: The atom or group of atoms responsible for the characteristic chemical properties of a compound — The functional group (e.g. −OH, −COOH, C=C) determines how a molecule reacts and is used to classify it into a homologous series.
Easy
2. A hydrocarbon contains only which two elements?
Carbon and hydrogen
Carbon and oxygen
Carbon and nitrogen
Hydrogen and oxygen
Answer: Carbon and hydrogen — By definition, a hydrocarbon is a compound made up of only carbon and hydrogen atoms.
Medium
3. Which of these best describes a homologous series?
A family of compounds with the same general formula and functional group, each differing by a CH2 unit
Compounds with the same molecular formula but different structures
Compounds containing only single carbon-carbon bonds
Compounds that all have the same boiling point
Answer: A family of compounds with the same general formula and functional group, each differing by a CH2 unit — A homologous series shares a general formula and functional group, with each successive member differing by CH2 and showing a gradual trend in physical properties.
