When it comes to fuel efficiency and engine performance, Octane Number and Cetane Number are two crucial parameters. While the Octane Number applies to petrol (gasoline) , the Cetane Number is relevant for diesel fuels . Understanding these values helps in choosing the right fuel for vehicles, improving combustion efficiency, and reducing engine knocking. What is the Octane Number? The Octane Number (Octane Rating) measures a fuel's resistance to knocking (or pre-ignition) in a petrol engine. Knocking occurs when the air-fuel mixture ignites prematurely, causing inefficient combustion and potential engine damage. Types of Octane Ratings There are three common octane ratings used worldwide: Research Octane Number (RON) – Measured under low-speed, low-load conditions. Motor Octane Number (MON) – Measured under high-speed, high-load conditions. Anti-Knock Index (AKI) – The average of RON and MON, commonly used in the US. Octane Number Scale The Octane Number is...

25 short question-answer  on Haloalkanes : Basic Concepts What are haloalkanes? → Organic compounds containing a halogen (X = F, Cl, Br, I) attached to an alkyl group. How are haloalkanes classified? → Based on the carbon to which halogen is attached: Primary (1°): R-CH₂-X Secondary (2°): R₂-CH-X Tertiary (3°): R₃-C-X Which is more reactive: alkyl halides or aryl halides? → Alkyl halides, because aryl halides have resonance stabilization. Which is the best leaving group among halogens? → I⁻ (Iodide) because it is the largest and weakest base. Why do haloalkanes have higher boiling points than alkanes? → Due to dipole-dipole interactions and van der Waals forces. Preparation of Haloalkanes How is chloromethane prepared from methane? → By free radical halogenation: CH₄ + Cl₂ → CH₃Cl + HCl (in sunlight) How can alcohols be converted to haloalkanes? → By using: HCl, HBr, or HI PCl₅, PCl₃, SOCl₂ (best method for Cl) What is the best me...