Zadanie 1d

(i) a strong acid ionizes/dissociates completely AND a weak acid ionizes/dissociates partially «in aqueous solution» ✔

(ii) M1: Lewis formula of NO₂⁻: N bonded to one O by a double bond and to the other O by a single bond, one lone pair on N, lone pairs completing each O, all in square brackets with a 1− charge «either resonance form; the charge may be shown on the singly bonded O without brackets» ✔

M2: molecular geometry bent/V-shaped «3 electron domains around N, one of them non-bonding» ✔

(iii) sp² ✔ «three electron domains around N: one N=O, one N–O and one lone pair»

(iv) M1: delocalization of electrons/of the negative charge «over the O–N–O unit» ✔

M2: resonance structures «two equivalent structures differing in which O carries the double bond, so both N–O bonds are identical and of intermediate length and strength» ✔

(i) [1] one marking point: both halves of the contrast are needed. (ii) [2] M1: correct Lewis formula (18 valence electrons); any combination of lines and dots is accepted; penalize missing brackets and/or missing negative charge, but the charge may be placed on the singly bonded O without brackets; either resonance form is accepted. M2: molecular geometry must follow from the Lewis formula drawn (ECF), so a structure with a different number of electron domains is marked for the geometry consistent with it. (iii) [1] sp2; ECF from the Lewis formula drawn in (ii) (three electron domains around N give sp2; a drawing with four domains would give sp3). (iv) [2] M1: delocalization of electrons or of the negative charge; M2: resonance structures (accept resonance hybrid); two equivalent N–O bonds of intermediate length may be offered as the consequence.