Waec Model Questions Vol1 2021 Chemistry Question 31

Practice objective / multiple choice question 31 from the 2021 Waec Model Questions Vol1 Chemistry examination.

Waec Model Questions Vol1 2021 Chemistry Objective / Multiple Choice Hard Difficulty
Question 31 WAEC_MODEL_QUESTIONS_VOL1 • 2021 • CHEMISTRY • objective

A 50.0 mL sample of an unknown monoprotic carboxylic acid solution has a pH of 3.00. The solution is titrated with 0.100 M NaOH and reaches the equivalence point after the addition of 5.00 mL of the base. At the half‑equivalence point the measured pH is 4.00. Determine (i) the acid dissociation constant Ka of the acid and (ii) the molar concentration of the acid in the original sample.

Answer Options

A. Ka = 1.0×10⁻³; concentration = 0.100 M
B. Ka = 5.0×10⁻⁵; concentration = 0.005 M
C. Ka = 2.0×10⁻⁴; concentration = 0.020 M
Correct Answer D. Ka = 1.0×10⁻⁴; concentration = 0.010 M
Correct Answer
D
Correct Option:
Ka = 1.0×10⁻⁴; concentration = 0.010 M

About This Question

This is Waec Model Questions Vol1 2021 Chemistry Question 31. It is one of the objective questions from the 2021 Waec Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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