The p-Block Elements Test - 5

Fluorine is the most electronegative element,  it shows only -1 oxidation state.

4F₂ + H₂S → SF₆ +  2 HF

The strongest lewis base is NI₃ due to lower electronegativity of I. So the tendency of trihalides of N decreases from NI₃ > NBr₃ > NCl₃ > NF₃ due to increase in electronegativity from I to F.

Higher oxidation state oxides are acidic while lower oxidation state oxides are basic. Intermediate oxidation state oxides are amphoteric. In other words, it behaves acidic with bases and as basic with acids.

The oxidation state of Cr in Cr₂O₃ is +3 , Vanadium in V₂O₅ is +5, Cl in Cl₂O₇ is +7 and Sn in SnO₂ is +4.

Phosphine smell like rotten fish due to the presence of substituted phosphine and diphosphine (P₂H₄). Pure phosphine has no characteristic smell.

Urea on reaction with NaOH liberates ammonia.
NH₂CONH₂ + 2NaOH → Na₂CO₃ + 2NH₃↑

O₃ reacts with KOH to form KO₃ potassium ozonide which is orange coloured solid and contains paramagnetic O^3- ion.
2KOH + 5O₃ → 2KO₃ + 5O₂ + H₂O

Stability of hydrides decreases down the group so most stable is H₂O. The thermal stability decreases as the atomic mass increases. Water dissociates at 2000⁰C while tellurium hydride, H₂Te decomposes at room temperature. This is due to an increase in the bond length of M-H (M- O, S, Se, Te).

Thus the thermal stability decreases as the atomic size increases. As with the increase in atomic size, the bond length also increases which decreases the thermal stability.