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?
Answer
The correct answer is B: Both Statement II and Statement III are correct but only one of them explains Statement I. Cement industry contributes approximately 7-8% of global CO2 emissions, so Statement I is correct. Statement II is correct — silica-bearing clay is indeed mixed with limestone in cement manufacturing.
A.Both Statement II and Statement III are correct and both of them explain Statement I
B.Both Statement II and Statement III are correct but only one of them explains Statement I✓ Correct
C.Only one of the Statements II and III is correct and that explains Statement I
D.Neither Statement II nor Statement III is correct
Explanation
Cement industry contributes approximately 7-8% of global CO2 emissions, so Statement I is correct. Statement II is correct — silica-bearing clay is indeed mixed with limestone in cement manufacturing. Statement III is also correct — during clinker production, limestone (CaCO3) is calcined to lime (CaO), releasing CO2. However, only Statement III explains the high carbon emissions of cement industry (calcination releases CO2 as a process emission). Mixing clay with limestone (Statement II) does not directly explain CO2 emissions. So both II and III are correct but only one explains Statement I.
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