12-Minute Test: Properties of Hydrocarbons - UPSC MCQ

Unsaturated hydrocarbons like ethyne also known as acetylene burn to produce a yellow sooty flame due to incomplete combustion in air.

The flame is sooty because the percentage of carbon is comparatively higher than that of alkanes and so does not get completely oxidized in air.

The combustion of methane produces the following:

• Carbon dioxide (CO₂)
• Water (H₂O)
• Heat
• Light

The chemical reaction can be summarised as:

CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g) + Heat + Light

Alkaline potassium permanganate is an effective oxidising agent.

• It converts alcohols into carboxylic acids.
• It is often used in reactions needing strong oxidation.

Alkaline potassium permanganate is a good oxidising agent.

Addition of hydrogen across C-C double bonds is called hydrogenation. Unsaturated hydrocarbons add hydrogen in the presence of catalysts such as nickel/palladium to give saturated hydrocarbons. Vegetable oils used for cooking are long unsaturated hydrocarbons which are healthy.

Incomplete combustion of fuel gives out sooty flame which contains unburnt carbon particles which deposits on the bottom of cooking utensils.

Oxidation is gain of oxygen. In this reaction oxygen is added to the reactant to form product. 

Saturated hydrocarbons contain C-C single bond and on complete combustion they produce large amounts of heat. The cooking gas used in house is Butane (C₄H₁₀) known as LPG or Methane (CH₄) known as CNG.

The chemical formula of benzene is C6H6, so it has six carbon atoms and six hydrogen atoms.

The reaction in which an element or molecule is added to unsaturated hydrocarbons is called addition reaction.

The reaction in which an element or molecule is added to unsaturated hydrocarbons is called addition reaction. In the above reaction unsaturated hydrocarbon is converted into saturated hydrocarbon.