Govt. Exams
Entrance Exams
Pt²⁺ has d⁸ configuration. With strong field Cl⁻, square planar geometry provides maximum CFSE and is thermodynamically favored.
[Cr(H₂O)₆]³⁺ is high spin with 3 unpaired electrons. CN⁻ is strong field ligand causing pairing. [Cr(NH₃)₆]³⁺ is intermediate.
In solid-state reduction, diffusion through the ash layer is often the rate-determining step, creating a diffusion barrier.
Larger alkali metal cations (K⁺, Rb⁺) can stabilize larger peroxide and superoxide anions due to better lattice energy matching.
In XeF₄, Xe has 8 valence electrons. 4 electrons form bonds with F atoms, leaving 2 lone pairs. With 4 bonding pairs and 2 lone pairs (octahedral electron geometry), the molecular geometry is square planar.
At such low HCl concentration (10⁻⁸ M), contribution of H⁺ from water ionization (10⁻⁷ M) cannot be ignored. Total [H⁺] ≈ 10⁻⁷ + 10⁻⁸ ≈ 1.1 × 10⁻⁷, giving pH ≈ 6.98.
BeCl₂ shows maximum covalent character among the options due to Be²⁺ ion's small size and high charge density, which polarizes the Cl⁻ ions significantly (Fajans rules).
In H₂S₂O₃ (thiosulfuric acid), two sulfur atoms have different oxidation states: one is +5 and one is -1. Average oxidation state = (+5-1)/2 = +2, but individual states are +5 and -1. Correct answer shows +3 as average consideration.
