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JEE Chemistry

Chemistry questions for JEE Main — Physical, Organic, Inorganic Chemistry.

143 Q 5 Topics Take Test
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Difficulty: All Easy Medium Hard 61–70 of 143
Topics in JEE Chemistry
In the extraction of iron from haematite using blast furnace, carbon monoxide acts as:
A A reducing agent
B An oxidizing agent
C A catalyst
D A flux
Correct Answer:  A. A reducing agent
EXPLANATION

CO reduces Fe₂O₃ to Fe by accepting oxygen: Fe₂O₃ + 3CO → 2Fe + 3CO₂. CO is the primary reducing agent at higher temperatures.

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Among the following oxides, which one is amphoteric?
A MgO
B Al₂O₃
C Na₂O
D Cl₂O₇
Correct Answer:  B. Al₂O₃
EXPLANATION

Al₂O₃ reacts with both strong acids and strong bases, exhibiting amphoteric character. MgO is basic, Na₂O is strongly basic, and Cl₂O₇ is acidic.

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Which of the following d-block elements has the configuration [Ar]3d⁵4s¹?
A Chromium
B Manganese
C Iron
D Vanadium
Correct Answer:  A. Chromium
EXPLANATION

Chromium has the electronic configuration [Ar]3d⁵4s¹ due to half-filled d-orbital stability, making it more stable than [Ar]3d⁴4s².

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Which of the following compounds would exhibit hydrogen bonding?
A CH₄
B HF
C CCl₄
D C₂H₆
Correct Answer:  B. HF
EXPLANATION

HF exhibits hydrogen bonding between H (bonded to highly electronegative F) and lone pairs on F of adjacent molecules.

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Which halogen has the lowest electronegativity?
A Fluorine
B Chlorine
C Bromine
D Iodine
Correct Answer:  D. Iodine
EXPLANATION

Iodine has the lowest electronegativity among halogens (2.5) due to its largest atomic radius and furthest valence electrons from nucleus.

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The ionization energy generally increases across a period because:
A Atomic radius increases
B Nuclear charge increases and atomic radius decreases
C Number of electrons decreases
D Shielding effect increases
Correct Answer:  B. Nuclear charge increases and atomic radius decreases
EXPLANATION

Across a period, increasing nuclear charge more significantly affects ionization energy than the slight increase in shielding, causing IE to increase.

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The white precipitate formed when AgNO₃ is added to a solution containing Cl⁻ ions is:
A Ag₂O
B AgCl
C Ag₃ClO₄
D AgNO₃
Correct Answer:  B. AgCl
EXPLANATION

AgCl is a white precipitate (Ksp = 1.8 × 10⁻¹⁰) formed due to the low solubility product of silver chloride.

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Which metal exhibits variable oxidation states primarily due to incomplete d-orbital filling?
A Calcium
B Iron
C Aluminum
D Sodium
Correct Answer:  B. Iron
EXPLANATION

Iron (Fe) exhibits variable oxidation states (+2 and +3) due to its incomplete d-orbitals, allowing electron transitions between different oxidation states.

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What is the coordination number of zinc in [Zn(CN)₄]²⁻?
A 2
B 4
C 6
D 8
Correct Answer:  B. 4
EXPLANATION

Zinc has a coordination number of 4 in this complex as four cyanide ligands are bonded to it. This follows the typical tetrahedral geometry for Zn²⁺.

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In the thermite reaction, which metal is oxidized?
A Iron
B Oxygen
C Aluminum
D Carbon
Correct Answer:  C. Aluminum
EXPLANATION

In the thermite reaction (2Al + Fe₂O₃ → Al₂O₃ + 2Fe), aluminum is oxidized from 0 to +3 oxidation state as it reduces Fe₂O₃.

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