Titration curve identifies weak base in flask titrated by strong acid

Steps:

• Analyze curve: starts at high pH (~11), gradual decrease, sharp drop at equivalence, then low pH.
• X in flask sets initial high pH, indicating base; gradual pre-equivalence drop suggests weak base.
• Y from burette causes sharp pH change, indicating strong acid.
• Match to options: weak base (ammonia) with strong acid (nitric).

Why A is correct:

• Ammonia (weak base, pKb ~4.75) titrated by nitric acid (strong acid) produces curve with buffer region before equivalence and sharp pH drop, per Henderson-Hasselbalch equation.

Why the others are wrong:

• B: Ethanoic acid is weak; weak-weak titration lacks sharp equivalence point.
• C: Not provided; insufficient information.
• D: KOH is strong base; curve would start at higher pH (~13) with immediate sharp drop, no buffer region.

Final answer: A