Types of Organic Reaction

How the real exam tests it

Questions from real CSCA papers that test this concept. Work each one out before you open the answer.

1. CSCA Chemistry April 2026 Past Paper
   Among the following organic reactions, the one that is an addition reaction is ( ).
   • A. Methane burning in oxygen
   • B. Ethylene reacting with hydrogen to produce ethane
   • C. Methane reacting with chlorine under illumination
   • D. Preparing ethylene from ethanol
   Show answer & solution

   Answer: B

   Answer: B Ethylene reacts with hydrogen to form ethane, which is an addition reaction.
   Take the full CSCA Chemistry April 2026 Past Paper — timed & graded
2. CSCA Chemistry March 2026 Past Paper
   Which is a substitution reaction?
   • A．Ethylene + hydrogen (addition)
   • B．Benzene + liquid bromine with iron catalyst
   • C．Ethanol combustion
   • D．Acetylene decolorizes acidified $\mathrm { KMnO } _ { 4 }$
   Show answer & solution

   Answer: B

   Benzene $+ \mathrm { Br } _ { 2 }$ (Fe catalyst): H replaced by $\mathrm { Br } =$ substitution. A: addition. C/D: oxidation. Answer: B.
   Take the full CSCA Chemistry March 2026 Past Paper — timed & graded