JAMB Chemistry 2019 Objective — Question 20

Question 20 of 40 from the Joint Admissions and Matriculation Board (JAMB) Chemistry 2019 Objective paper, with the correct answer and a full explanation.

25cm³ of 1.5m solution of NaCl is added to 50cm³ of 3m NaCl. The molar concentration of the resulting solution is

A. 2.5mCorrect
B. 3m
C. 2.25m
D. 4.5m

Explanation

Moles from sample 1 = 1.5×(25/1000) = 0.0375mol. Moles from sample 2 = 3×(50/1000) = 0.15mol. Total moles = 0.1875mol. Total volume = 75cm³ = 0.075dm³. Concentration = 0.1875/0.075 = 2.5moldm⁻³.

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