Central Exam — General Science — Chemistry
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Q.1
Medium
Chemistry
In the reaction between potassium permanganate and oxalic acid in acidic medium, what is the ratio of KMnO₄ to H₂C₂O₄ in the balanced equation?
Correct Answer:
B. 2:5
Explanation:
The balanced equation for this redox reaction in acidic medium is: 2KMnO₄ + 5H₂C₂O₄ + 3H₂SO₄ → K₂SO₄ + 2MnSO₄ + 10CO₂ + 8H₂O.
Potassium permanganate acts as an oxidizing agent (Mn⁷⁺ → Mn²⁺), while oxalic acid is oxidized (C²⁺ → C⁴⁺), giving the 2:5 molar ratio.
Q.2
Medium
Chemistry
What is the hybridization state of the central carbon atom in the carbonate ion (CO₃²⁻)?
Correct Answer:
B. sp²
Explanation:
In the carbonate ion CO₃²⁻, the central carbon atom forms three sigma bonds with oxygen atoms and is involved in resonance structures with delocalized pi electrons.
This trigonal planar geometry requires sp² hybridization, with three hybrid orbitals arranged at 120° angles and one unhybridized p orbital for pi bonding.