UPSC Prelims 2025 · Question 11 of 100

UPSC Prelims 2025 question on Cement Industry CO2 Emissions

Consider the following statements:

Statement I:
Studies indicate that carbon dioxide emissions from cement industry account for more than 5% of global carbon emissions.

Statement II:
Silica-bearing clay is mixed with limestone while manufacturing cement.

Statement III:
Limestone is converted into lime during clinker production for cement manufacturing.

Which one of the following is correct in respect of the above statements?

  1. Both Statement II and Statement III are correct and both of them explain Statement I
  2. Both Statement II and Statement III are correct but only one of them explains Statement I
  3. Only one of the Statements II and III is correct and that explains Statement I
  4. Neither Statement II nor Statement III is correct
Show answer

Answer: A. Both Statement II and Statement III are correct and both of them explain Statement I

Analysis

Both Statement II and III are correct and both explain Statement I → Option (a).

Statement by statement

Statement I – CORRECT: The high-temperature process for manufacturing cement accounts for roughly 8% of the world's anthropogenic carbon dioxide emissions and consumes 2–3% of global energy supply. Hence statement I about >5% is correct.

Statement II – CORRECT: Mixing silica-based clay with limestone during cement production leads to the release of CO2, confirming silica-bearing clay is mixed with limestone.

Statement III – CORRECT: The calcination process (clinker production) converts calcium carbonate (CaCO3), the principal component of limestone, to calcium oxide (CaO), releasing CO2 — so limestone is indeed converted into lime.

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