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JAMB Chemistry 1990 Question 19

Question 19

Volumetric Analysis

2.0 g of a monobasic acid was made up to 250 cm3 with distilled water. 25.00 cm3 of this solution required 20.00 cm3 of 0.1 M NaOH solution for complete neutralization. The molar mass of the acid is

  1. A.200 g
  2. B.160 g
  3. C.100 g
  4. D.50 g
Show the answer and explanation

Answer: C (100 g)

Explanation

Moles of NaOH = 0.1 × 20/1000 = 0.002, so 25 cm3 holds 0.002 mol of acid and 250 cm3 holds 0.02 mol. Molar mass = 2.0 ÷ 0.02 = 100 g/mol.