Chemistry - GENERAL CHEMISTRY Question with Solution | TestHub

Option (A) is correct: Using the relation $\Delta H_{sol}=\Delta H_{lattice}+\Delta H_{hyd}$, we get $4=788+\Delta H_{hyd}⟹\Delta H_{hyd}=-784kJ/mol$.

Option (B) is incorrect: For isoelectronic species (N³⁻, O²⁻, F⁻), the ionic radius decreases as nuclear charge increases, so the correct order is N³⁻ > O²⁻ > F⁻.

Option (C) is correct: The conversion A²⁻(g) $\to$ A⁴⁺(g) involves EGE₂, EGE₁, IE₁, IE₂, IE₃, and IE₄; therefore, only 2 enthalpies (IE₅ and IE₆) are not associated.

Option (D) is correct: The 9th period fills the $9s,6g,7f,8d$, and $9p$ subshells, containing a total of $1+9+7+5+3=25$ orbitals (changing electron capacity per orbital doesn't alter the number of orbitals).