MDCAT Chemistry — Chemistry of Hydrocarbons
Chemistry of Hydrocarbons is a core Chemistry topic in the PMDC MDCAT syllabus, covering 19 subtopics. Below are the subtopics to revise, how often the topic appears in past papers, and real past-paper MCQs to try.
Subtopics (19)
- Acidity of Alkynes
- Chemical Reactions of Benzene
- Chemistry of Alcohols (Ethers, Esters)
- Chemistry of Alkenes
- Effect of Substituents on Benzene
- Free Radical Mechanism
- Friedel-Crafts alkylation reaction
- MOT of Benzene, Resonance, Resonance Energy
- Nomenclature of Alkanes
- Nomenclature of Alkenes
- Nomenclature of Alkynes
- Nucleophilic Addition Reactions
- Octane Number and Cracking
- Preparation of Alkanes
- Preparation of Alkynes
- Reactivity of Benzene
- Shapes of Alkenes (Sigma/Pi Bonds)
- Structure and Reactivity of Alkenes
- Substitution vs Addition Reactions
How Chemistry of Hydrocarbons is tested
Across the 16 MDCAT past papers on ParhaiKrlo, Chemistry of Hydrocarbons accounts for 86 questions. It appears in all 16, about 5.4 questions a paper. The heaviest was MDCAT 2014, with 12 questions, and the most recent is MDCAT 2025, with 5.
| Paper | Questions |
|---|---|
| MDCAT 2025 | 5 |
| MDCAT 2024 | 4 |
| MDCAT 2023 | 7 |
| MDCAT 2022 | 7 |
| MDCAT 2019 | 4 |
| MDCAT 2018 | 6 |
| MDCAT 2017 | 9 |
| MDCAT 2016 | 7 |
| MDCAT 2015 | 6 |
| MDCAT 2014 | 12 |
| MDCAT 2013 | 2 |
| MDCAT 2012 | 3 |
| MDCAT 2011 | 3 |
| MDCAT 2010 | 4 |
| MDCAT 2009 | 4 |
| MDCAT 2008 | 3 |
Chemistry of Hydrocarbons MCQs from the MDCAT past papers
Try each one before opening the answer. Each comes with a short explanation.
- Q1 · MDCAT 2025 · Chemistry of Hydrocarbons
Conversion of a dihaloalkane into an alkyne does not involve:
- A.Addition
- B.Elimination
- C.Base
- D.Heat
Show answer
Answer: A. Addition — Converting a dihaloalkane to an alkyne does not involve an addition reaction — it requires elimination (double dehydrohalogenation).
- Q2 · MDCAT 2024 · Chemistry of Hydrocarbons
Which of the following is an example of substituent group which release electrons to benzene ring:
- A.−CN
- B.−NR₃⁺
- C.−NH₂
- D.−NO₂
Show answer
Answer: C. −NH₂ — -NH2 is an electron-releasing (donating) group on a benzene ring, unlike -CN, -NR3+, and -NO2.
- Q3 · MDCAT 2023 · Chemistry of Hydrocarbons
Which of the following reagents can be used to distinguish between 1-Pentyne and 2-Pentyne?
- A.AgNO₃ + NH₄OH
- B.1% alkaline dilute KMnO₄
- C.Br₂/CCl₄
- D.K₂Cr₂O₇ + H₂SO₄
Show answer
Answer: A. AgNO₃ + NH₄OH — Ammoniacal silver nitrate (Tollens' reagent) distinguishes a terminal alkyne (1-pentyne) from an internal one (2-pentyne) via a precipitate with the terminal alkyne's acidic C-H.