The P-Block Elements (XII)

Fluorine does not show variable oxidation state due to absence of vacant-d orbitals

Magic acid ( FSO ₃H·SbF ₅) is a superacid consisting of a mixture, most commonly in a 1:1 molar ratio, of fluorosulfuric acid ( HSO ₃F) and antimony pentafluoride ( SbF ₅). The super acidity of super acid is due to the formation of ${\mathrm{H}}_2{\mathrm{SO}}_3{\mathrm{F}}^{+}$ion .

Fluorine does not show variable oxidation state due to absence of vacant-d orbitals

In a polar solvent, PCl₅ undergoes auto-ionization to form ionic species [PCl₄]⁺ [PCl₆]^–. Upon fluorination, fluorine, being more electronegative and smaller, tends to replace chlorine in the coordination sphere. This results in the formation of ionic isomers such as [PCl₄]⁺ [PCl₄F₂]^– and [PCl₄]⁺ [PF₆]^–.

Oxygen, sulphur, selenium, and tellurium can show the −2 oxidation state. However, polonium (being a heavier, more metallic Group 16 element) does not typically exhibit a stable −2 state; its common oxidation states are +2 and +4 (and it can reach +6 in some compounds), but the −2 state is unknown for Po.

Oxygen, sulphur, selenium, and tellurium can show the −2 oxidation state. However, polonium (being a heavier, more metallic Group 16 element) does not typically exhibit a stable −2 state; its common oxidation states are +2 and +4 (and it can reach +6 in some compounds), but the −2 state is unknown for Po.

${\mathrm{SO}}_2$ can oxidise as well as reduce. Hence it can act as both oxidising and reducing agent.

The main element in the apatite family is phosphorus (P), and its first ionization enthalpy is 1012 kJ/mol.

Nitrogen (Z=7) forms strong pπ−pπ bonds (e.g., N≡N in N₂) due to its small size and effective orbital overlap. It also has the strongest basic hydride (NH₃) because of its highly available lone pair. Heavier Group-15 elements (P, As, Sb) have weaker bonding and less basic hydrides. Correct answer: (A) Z=7.

The actual acid strength order for hydrogen halides is HI > HBr > HCl > HF, because the H–I bond is the weakest and easiest to ionize.

The ionization energy decreases down the group, hence Bi has the lowest energy among the group -15 elements.

Reaction:

$3{\mathrm{HNO}}_2\to 2\mathrm{NO}+{\mathrm{HNO}}_3+{\mathrm{H}}_2\mathrm{O}$

In aqueous solution, HNO₃ dissociates to H₃O⁺ and ${\mathrm{NO}}_3^{-}$.

So the species formed are H₃O⁺, ${\mathrm{NO}}_3^{-}$ and NO.

Oxidising and acidic

The large difference in melting and boiling points between oxygen $\left(O_2\right)$ and sulphur $\left(S_8\right)$ is primarily due to their atomicity.

(A) true—nonmetals are more electronegative; (C) true—large ΔEN between reactive metals and nonmetals gives ionic compounds; (B) false—nonmetals have higher ionization enthalpy; (D) false—nonmetal oxides are generally acidic; (E) false—metal oxides are typically basic/amphoteric.

Nitrogen (Z=7) forms strong pπ−pπ bonds (e.g., N≡N in N₂) due to its small size and effective orbital overlap. It also has the strongest basic hydride (NH₃) because of its highly available lone pair. Heavier Group-15 elements (P, As, Sb) have weaker bonding and less basic hydrides. Correct answer: (A) Z=7.

Fluorine has no vacant d-orbitals so no electron excitation is possible and so it does not exhibit variable oxidation states.

The single N-N bond is weakest in E-E bond of group 15 elements due to interelectronic repulsions.

Maxium covalency of Nitrogen is 4.

anomalous behavior of oxygen is primarily due to its small atomic size and high electronegativity, which influence its properties like strong hydrogen bonding in water, its limited covalency, and its tendency to form multiple bonds less easily than other elements in its group. The absence of vacant d-orbitals in its valence shell also contributes to these differences, preventing it from expanding its covalency beyond four, unlike other group 16 elements.

Statement (D) is incorrect: The stability of the +5 oxidation state decreases down Group 15, while the stability of the +3 oxidation state increases. This is due to the inert pair effect, where the outermost s-electrons become reluctant to participate in bonding for the heavier elements.

Statement (E) is incorrect: Nitrogen (N) is in the second and has only four available orbitals (one s and three p) in its valence shell, allowing a maximum covalency of 4. It cannot expand its octet to a covalency of 6 because it lacks d-orbitals.

In SO₂, sulfur has an oxidation number of +4. It acts as a reducing agent by increasing its oxidation number to +6 ( forming H₂SO₄) and as an oxidizing agent by decreasing its oxidation number to 0 ( forming sulfur). Thus, SO₂ shows both behaviors.

Hydrolysis of interhalogen compounds:

$\mathrm{ICl}+{\mathrm{H}}_2\mathrm{O}\to \mathrm{HIO}+\mathrm{HCl}$ (produces IO^–)

${\mathrm{ClF}}_3+2{\mathrm{H}}_2\mathrm{O}\to {\mathrm{HClO}}_2+3\mathrm{HF}$ (produces ${\mathrm{ClO}}_2^{-}$)

${\mathrm{BrF}}_5+3{\mathrm{H}}_2\mathrm{O}\to {\mathrm{HBrO}}_3+5\mathrm{HF}$ (produces ${\mathrm{BrO}}_3^{-}$)