Official Answer Key & Detailed Solution
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Official UPSC Answer KeyUPSC Prelims 1998 • Science and Technology
Correct Answer: Option (D) — A-4; B-3; C-1; D-2
Concept & Option Breakdown
Standard Reference Verified- Blue vitriol is copper sulphate pentahydrate ($\text{CuSO}_4\cdot 5\text{H}_2\text{O}$) (A matches 4).
- Epsom salt is magnesium sulphate heptahydrate ($\text{MgSO}_4\cdot 7\text{H}_2\text{O}$) (B matches 3).
- Baking soda is sodium bicarbonate ($\text{NaHCO}_3$) (C matches 1).
- Caustic soda is sodium hydroxide ($\text{NaOH}$) (D matches 2). Thus, the correct sequence is A-4; B-3; C-1; D-2.
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