Answer is: A) SrCl₂ and E) KNO₃.
A) Strontium chloride (SrCl₂) is a salt of a strong acid and strong base, strontium cations (Sr²⁺) and chloride anions (Cl⁻) react very little with water, so solution is neutral.
B) Prussic acid (HCN) is acidic, because it dissociates on H⁺ ions.
C) Strontium hydroxide (Sr(OH)₂) is basic, because it dissociates on OH⁻ ions.
D) Ammonium chloride (NH₄Cl) is a salt of a strong acid and weak base. Weak base (NH₄⁺) reacts with water and give acidic solution: NH₄⁺ + H₂O ⇄ NH₃ + H₃O⁺.
E) Potassium nitrate (KNO₃) is a salt of a strong acid and strong base, potassium cations (K⁺) and nitrate anions (NO₃⁻) react very little with water, so solution is neutral.
F) Potassium cyanide (KCN) is salt of a weak acid and strong base, solution is basic.
