Govt. Exams
Entrance Exams
Molybdenum forms very stable +6 oxidation state compounds like MoO₃ and MoO₄²⁻. This is due to d-block stability and orbital availability.
Lattice energy is inversely proportional to interionic distance. Cl⁻ is smaller than I⁻, so NaCl has higher lattice energy.
[CoF₆]³⁻ is high spin with 4 unpaired electrons (d⁶). [Fe(CN)₆]⁴⁻ is low spin with 0 unpaired electrons. [Fe(H₂O)₆]²⁺ has 4 unpaired electrons but [CoF₆]³⁻ has higher magnetic moment.
Na₂CO₃ solution is basic because CO₃²⁻ hydrolyzes to produce OH⁻ ions. It's the salt of weak acid and strong base.
Zn is more reactive than hydrogen and can displace it from dilute acids. Cu, Ag, and Au are less reactive than hydrogen.
The orange color arises from charge transfer between oxygen and chromium, not from d-d transition within Cr³⁺.
Excess oxygen converts P₄ to P₄O₁₀ (phosphorus pentoxide). Limited oxygen gives P₄O₆.
+3 is the most stable oxidation state for Cr with d³ configuration. Cr³⁺ complexes are highly stable.
Be and Al show diagonal relationship due to similar charge-to-radius ratio. Both form covalent compounds and amphoteric oxides.
Borax solution is basic because borate ions undergo hydrolysis: BO₃³⁻ + H₂O ⇌ HBO₃²⁻ + OH⁻, producing OH⁻ ions and making the solution basic.
