Answer
(a) Neutral: pH = 7
(b) Acidic: pH < 7
(c) Neutral: pH = 7
(d) Acidic: pH < 7
Work Step by Step
1. Identify if each ion is a strong or weak acid or base, or if it does not hydrolyze.
(a) $K^+$ does not hydrolyze (Conjugate acid from strong base: KOH)
$Br^-$ does not hydrolyze (Conjugate base from strong acid: HBr)
(b) $Al^{3+}$ hydrolyzes to produce $H^+$ (Small metal ion with high charge)
$NO_3^-$ does not hydrolyze (Conjugate base from strong acid: $HNO_3$)
(c) $Ba^{2+}$ does not hydrolyze (Conjugate acid from strong base: $Ba(OH)_2$)
$Cl^-$ does not hydrolyze (Conjugate base from strong acid: HCl)
(d) $Bi^{3+}$ hydrolyzes to produce $H^+$ (Small metal ion with high charge)
$NO_3^-$ does not hydrolyze (Conjugate base from strong acid: $HNO_3$)
2. If neither the anion nor the cation hydrolyzes, the pH of the aqueous solution will be neutral (7). If the solution will produce only $H^+$, the aqueous solution will be acidic: pH < 7.
(a) Neutral: pH = 7
(b) Acidic: pH < 7
(c) Neutral: pH = 7
(d) Acidic: pH < 7
