Which of the following reactions is an example of a thermal decomposition process used in the industrial manufacture of cement?

The correct option is Heating calcium carbonate to form calcium oxide and carbon dioxide.

Explanation

Thermal decomposition is a type of chemical reaction where a single reactant breaks down into two or more simpler products upon the application of heat. Since energy is required to break the bonds, these reactions are endothermic in nature.

Analysis of Options:

• Heating calcium carbonate to form calcium oxide and carbon dioxide is Correct: Heating calcium carbonate (limestone) results in its decomposition into calcium oxide (quick lime) and carbon dioxide. This specific thermal decomposition reaction is fundamental to the cement industry, as calcium oxide is a primary raw material for cement manufacturing.
  Reaction: CaCO₃(s) &xrightarrow{\Delta} CaO(s) + CO₂(g)
• Electrolysis of water to form hydrogen and oxygen is Incorrect: The breakdown of water into hydrogen and oxygen is achieved by passing an electric current through it. This is classified as electrolytic decomposition (electrolysis), not thermal decomposition.
• Decomposition of silver chloride in sunlight is Incorrect: The decomposition of silver chloride into silver and chlorine occurs due to exposure to sunlight. This is an example of photochemical decomposition.
• Reaction of iron with copper sulphate solution is Incorrect: The reaction of iron with copper sulphate is a displacement reaction, where a more reactive metal (iron) displaces a less reactive metal (copper) from its salt solution. It does not involve decomposition.

Key Takeaway:
Thermal decomposition is distinct from electrolytic or photochemical decomposition as it relies exclusively on heat energy. The calcination of limestone to produce quick lime is a prominent industrial application of this principle.