UPSC CSE Prelims
Question 87
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?
View correct answer and explanation
Correct answer: A
Correct Option: A (Both Statement II and Statement III are correct and both of them explain Statement I)
Explanation: Cement manufacturing emits substantial CO₂ both from heating limestone to make lime and from fuel use. Mixing limestone with silica-bearing materials supports clinker production, and calcination chemically releases CO₂.
Statement / Pair / Item-wise Analysis:
I: True-cement's share of global CO₂ emissions exceeds 5%.
II: True-clay supplies silica and alumina for clinker.
III: True-limestone (CaCO₃) decomposes into CaO and CO₂; both production processes explain emissions.
Option-wise Analysis:
A. Correct-this matches the facts and the item-wise assessment above.
B. Incorrect-this wrongly treats both supporting statements as valid or assigns an incorrect explanatory relationship.
C. Incorrect-this misstates how many supporting statements are true and explanatory.
D. Incorrect-the item analysis identifies at least one supporting statement as valid.