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

Which celestial phenomenon occurs when the Moon passes between the Earth and the Sun, blocking the Sun's light and casting a shadow on Earth?

Accepted Answer

Correct answer: A. Solar Eclipse — A solar eclipse happens when the Moon's orbit places it directly between Earth and the Sun, creating a shadow on Earth's surface. This is distinct from a lunar eclipse where Earth blocks sunlight from reaching the Moon, and from penumbral or annular eclipses which are specific types with different characteristics.

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B. Lunar Eclipse

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C. Penumbral Eclipse

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D. Annular Eclipse

Question 7

The escape velocity from the surface of a planet depends on which two fundamental properties of that planet?

Accepted Answer

Correct answer: B. Mass and radius — Escape velocity is mathematically derived as v = √(2GM/R), where G is gravitational constant, M is the planet's mass, and R is its radius. These two properties directly determine the gravitational field strength at the planet's surface, which defines the minimum velocity needed to escape gravitational attraction.

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A. Radius and temperature

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C. Density and temperature

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D. Atmospheric pressure and mass

Question 8

Which of the following statements about the Oort Cloud is incorrect?

Accepted Answer

Correct answer: D. It has been directly observed through telescopes and contains approximately 1 trillion objects — The Oort Cloud remains theoretical and has never been directly observed; we infer its existence from comet trajectories and orbital studies. While estimates suggest it contains billions to trillions of icy bodies, these objects are too distant and too small to be directly observed with current technology, making option D the incorrect statement among the given choices.

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A. It is a theoretical spherical shell of icy bodies surrounding our solar system

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B. It extends approximately 100,000 to 200,000 AU from the Sun

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C. It is the primary source of long-period comets

General Science - MCQ Practice Questions