Chemistry carries the highest scoring potential in JEE for anyone who keeps the three branches separate in revision. This set covers physical chemistry numericals, organic reaction mechanisms and named reactions, and inorganic chemistry including periodic trends, chemical bonding and coordination compounds. Organic questions show the mechanism arrow by arrow, so the reasoning transfers to reactions you have not seen before.
SF₆ has 6 bonding pairs and 0 lone pairs on S. Coordination number = 6, requiring sp³d² hybridization with octahedral geometry.
Q.122Medium
Which compound shows the phenomenon of disproportionation?
Answer: C
H₂O₂ disproportionates: H₂O₂ → H₂O + ½O₂. NaClO: 3ClO⁻ → 2Cl⁻ + ClO₃⁻. Both show disproportionation.
Q.123Medium
The magnetic moment of [Fe(CN)₆]⁴⁻ is approximately:
Answer: A
CN⁻ is a strong field ligand causing pairing in d-orbitals. Fe²⁺ becomes diamagnetic with μ = 0 B.M. (t₂g⁶eg⁰ configuration).
Q.124Medium
In the extraction of copper using electrorefining, what is the anode material?
Answer: B
Blister copper (impure copper from smelting) acts as the anode. Pure copper is the cathode. Impurities fall as anode mud.
Q.125Medium
Which of the following is a non-stoichiometric compound?
Answer: B
Fe₀.₉₅O is a non-stoichiometric compound with variable composition. It contains both Fe²⁺ and Fe³⁺ ions due to defects in crystal structure.
Q.126Medium
Which statement about borax is correct?
Answer: B
Borax is a complex borate with formula Na₂B₄O₅(OH)₄·8H₂O, containing both triangular BO₃ and tetrahedral BO₄ units.
Q.127Medium
The reduction potential of Fe³⁺/Fe²⁺ is +0.77 V. This indicates:
Answer: C
Positive E° means Fe³⁺ is easily reduced and Fe²⁺ is easily oxidized. Fe³⁺ is a strong oxidizing agent relative to Fe²⁺.
Q.128Medium
The spin-only magnetic moment of Fe²⁺ in its ground state is approximately:
Answer: B
Fe²⁺ has 4 unpaired electrons (d⁶ configuration). Magnetic moment = √[n(n+2)] = √[4×6] = 4.90 BM
Q.129Medium
The crystal field splitting energy (Δ) for [Co(H₂O)₆]²⁺ is approximately 9,300 cm⁻¹. The complex will be:
Answer: A
Co²⁺ is d⁷. Water is a weak field ligand with small Δ, resulting in high spin configuration (t₂g⁵ eg²) with 4 unpaired electrons.
Q.130Medium
Which of the following lanthanides has the configuration [Xe]4f⁷6s²?
Answer: A
Europium (Eu) has atomic number 63 and configuration [Xe]4f⁷6s², with a half-filled f-orbital making it particularly stable.
Q.131Medium
The solubility product of AgCl at 25°C is 1.8 × 10⁻¹⁰. In 0.1 M NaCl solution, the concentration of Ag⁺ will be:
Answer: A
Ksp = [Ag⁺][Cl⁻] = 1.8 × 10⁻¹⁰. With [Cl⁻] = 0.1 M, [Ag⁺] = Ksp/[Cl⁻] = 1.8 × 10⁻¹⁰/0.1 = 1.8 × 10⁻⁹ M
Q.132Medium
The geometry of [PdCl₄]²⁻ complex is:
Answer: B
Pd²⁺ is d⁸ with strong field preference. It forms square planar geometry with Cl⁻ (weak field ligand) due to crystal field stabilization.
Q.133Medium
Which of the following statements about diborane (B₂H₆) is incorrect?
Answer: C
B₂H₆ has a bridged structure with 3D geometry, not planar. It contains bridging hydrogens forming 3-center-2-electron bonds.
Q.134Medium
The complex [Ni(CN)₄]²⁻ is diamagnetic. This indicates:
Answer: B
Ni²⁺ with strong field CN⁻ ligands shows diamagnetism (d⁸ with all paired electrons) in square planar geometry (dsp² hybridization).
Q.135Medium
In the preparation of chlorine by oxidizing HCl with MnO₂, the oxidation state of Mn changes from:
Answer: B
MnO₂ (Mn⁴⁺) acts as oxidizing agent, reducing Cl⁻ to Cl₂. Mn⁴⁺ gains 2 electrons, reducing to Mn²⁺.
Q.136Medium
Which of the following factors does NOT affect the magnitude of crystal field splitting (Δ)?
Answer: C
Crystal field splitting depends on ligand strength, metal ion charge, and geometry, but NOT on the mass of the metal ion.
Q.137Medium
Which of the following elements forms the most stable +6 oxidation state in its compounds?
Answer: C
Tungsten forms the most stable +6 oxidation state compounds like WO₃ and WCl₆. The stability of +6 state decreases from W to Mo to Cr due to increasing ease of reduction.
Q.138Medium
Which transition metal forms a complex with CO that has maximum carbonyl stretching frequency?
Answer: C
Manganese with lower electron density shows weaker back-bonding, resulting in higher CO stretching frequency. The order is Mn > Co > Fe > Ni based on back-bonding strength.
Q.139Medium
The magnetic moment of [Fe(H₂O)₆]²⁺ complex is approximately:
Answer: D
Fe²⁺ has d⁶ configuration. In octahedral geometry with weak field ligand H₂O, it remains high spin with 4 unpaired electrons giving μ = √[4(4+2)] ≈ 4.90 BM, but aqua complex shows ~5.92 BM.
Q.140Medium
Which of the following chlorides is most covalent in nature?
Answer: D
SiCl₄ is most covalent due to small Si⁴⁺ size and high charge density. Covalent character increases: NaCl < MgCl₂ < AlCl₃ < SiCl₄.
