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JEE Chemistry
Inorganic Chemistry

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

49 Q 5 Topics Take Mock Test
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Topics in JEE Chemistry
The crystal field splitting energy (Δ) for [Co(H₂O)₆]²⁺ is approximately 9,300 cm⁻¹. The complex will be:
A High spin with 4 unpaired electrons
B Low spin with 2 unpaired electrons
C High spin with 3 unpaired electrons
D Cannot be determined
Correct Answer:  A. High spin with 4 unpaired electrons
EXPLANATION

Co²⁺ is d⁷. Water is a weak field ligand with small Δ, resulting in high spin configuration (t₂g⁵ eg²) with 4 unpaired electrons.

Test
The spin-only magnetic moment of Fe²⁺ in its ground state is approximately:
A 2.82 BM
B 4.90 BM
C 5.92 BM
D 3.87 BM
Correct Answer:  B. 4.90 BM
EXPLANATION

Fe²⁺ has 4 unpaired electrons (d⁶ configuration). Magnetic moment = √[n(n+2)] = √[4×6] = 4.90 BM

Test
The reduction potential of Fe³⁺/Fe²⁺ is +0.77 V. This indicates:
A Fe³⁺ is easily reduced
B Fe²⁺ is easily oxidized
C Both A and B
D Neither A nor B
Correct Answer:  C. Both A and B
EXPLANATION

Positive E° means Fe³⁺ is easily reduced and Fe²⁺ is easily oxidized. Fe³⁺ is a strong oxidizing agent relative to Fe²⁺.

Test
Which statement about borax is correct?
A It is a simple tetrahedral borate
B Its formula is Na₂B₄O₅(OH)₄·8H₂O
C It contains only BO₃ units
D It is insoluble in water
Correct Answer:  B. Its formula is Na₂B₄O₅(OH)₄·8H₂O
EXPLANATION

Borax is a complex borate with formula Na₂B₄O₅(OH)₄·8H₂O, containing both triangular BO₃ and tetrahedral BO₄ units.

Test
Which of the following is a non-stoichiometric compound?
A NaCl
B Fe₀.₉₅O
C CaCO₃
D H₂O
Correct Answer:  B. Fe₀.₉₅O
EXPLANATION

Fe₀.₉₅O is a non-stoichiometric compound with variable composition. It contains both Fe²⁺ and Fe³⁺ ions due to defects in crystal structure.

Test
In the extraction of copper using electrorefining, what is the anode material?
A Pure copper
B Blister copper
C Graphite
D Iron
Correct Answer:  B. Blister copper
EXPLANATION

Blister copper (impure copper from smelting) acts as the anode. Pure copper is the cathode. Impurities fall as anode mud.

Test
The magnetic moment of [Fe(CN)₆]⁴⁻ is approximately:
A 0 B.M.
B 2.82 B.M.
C 4.90 B.M.
D 5.92 B.M.
Correct Answer:  A. 0 B.M.
EXPLANATION

CN⁻ is a strong field ligand causing pairing in d-orbitals. Fe²⁺ becomes diamagnetic with μ = 0 B.M. (t₂g⁶eg⁰ configuration).

Test
Which compound shows the phenomenon of disproportionation?
A H₂O₂
B NaClO
C Both A and B
D Neither A nor B
Correct Answer:  C. Both A and B
EXPLANATION

H₂O₂ disproportionates: H₂O₂ → H₂O + ½O₂. NaClO: 3ClO⁻ → 2Cl⁻ + ClO₃⁻. Both show disproportionation.

Test
The hybridization of sulfur in SF₆ is:
A sp³
B sp³d
C sp³d²
D d²sp³
Correct Answer:  C. sp³d²
EXPLANATION

SF₆ has 6 bonding pairs and 0 lone pairs on S. Coordination number = 6, requiring sp³d² hybridization with octahedral geometry.

Test
Which halide of boron exists as a dimer in the gaseous state?
A BF₃
B BCl₃
C BBr₃
D BI₃
Correct Answer:  B. BCl₃
EXPLANATION

BCl₃ forms a dimer (B₂Cl₆) in gaseous state due to bridging chlorine atoms. BF₃ remains monomeric due to strong B-F bonds and p-p repulsion.

Test
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