General Science — MCQ Practice Questions & Answers

Question 1

Which of the following elements has the highest electronegativity value on the Pauling scale?

Accepted Answer

Correct answer: A. Fluorine — Fluorine has the highest electronegativity value of 3.98 on the Pauling scale, making it the most electronegative element. This is because it has the smallest atomic radius and the highest effective nuclear charge among all elements, causing it to attract electrons most strongly in a chemical bond.

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B. Oxygen

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C. Chlorine

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D. Nitrogen

Question 2

In the reaction between potassium permanganate and oxalic acid in acidic medium, what is the ratio of KMnO₄ to H₂C₂O₄ in the balanced equation?

Accepted Answer

Correct answer: B. 2:5 — 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.

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A. 1:2

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C. 3:5

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D. 5:2

Question 3

Which of the following compounds exhibits both ionic and covalent bonding characteristics and is commonly used in coordination chemistry?

Accepted Answer

Correct answer: B. Potassium hexacyanoferrate(III) — Potassium hexacyanoferrate(III) contains both ionic bonds (between K⁺ and the [Fe(CN)₆]³⁻ complex) and covalent bonds (between Fe and CN ligands, and within the CN groups). This complex salt is extensively used in coordination chemistry and analytical procedures like the Prussian blue test.

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A. Sodium chloride

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C. Carbon dioxide

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D. Calcium oxide

Question 4

What is the hybridization state of the central carbon atom in the carbonate ion (CO₃²⁻)?

Accepted Answer

Correct answer: B. sp² — 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.

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A. sp

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C. sp³

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D. sp³d

Question 5

Which of the following substances will have the lowest lattice enthalpy among ionic compounds?

Accepted Answer

Correct answer: C. CsI — Lattice enthalpy depends inversely on ionic radius and directly on ionic charge. CsI has the lowest lattice enthalpy (~604 kJ/mol) because both Cs⁺ and I⁻ are large ions with 1+ and 1- charges respectively. In contrast, MgO has very high lattice enthalpy due to small, highly charged ions (Mg²⁺ and O²⁻), while NaCl and CaF₂ have intermediate values.

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A. NaCl

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B. MgO

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D. CaF₂

Question 6

Chemical formula of water?

Accepted Answer

Correct answer: B. H2O — Water = H₂O.

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A. HO

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C. H2O2

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D. HO2

Question 7

Atomic number of Carbon?

Accepted Answer

Correct answer: A. 6 — Carbon atomic number = 6.

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B. 8

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C. 12

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D. 14

Question 8

Liquid to gas process?

Accepted Answer

Correct answer: C. Evaporation — Evaporation = liquid to gas.

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A. Condensation

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B. Precipitation

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D. Sublimation

General Science - MCQ Practice Questions