Neco 2019 Chemistry Question 42

Practice objective / multiple choice question 42 from the 2019 Neco Chemistry examination.

Neco 2019 Chemistry Objective / Multiple Choice Medium Difficulty
Question 42 NECO • 2019 • CHEMISTRY • objective

A 500 g sample of water (\(K_b = 0.512\) \(^\circ\)C·kg·mol^{-1}) contains an unknown non‑volatile solute of molar mass 58.44 g·mol^{-1}. The solution shows a boiling‑point elevation of 1.5 \(^\circ\)C. After adding 200 g of water, the elevation becomes 1.07 \(^\circ\)C. (a) Calculate the mass of solute present. (b) Determine the percentage decrease in the boiling‑point elevation after dilution.

Answer Options

A. Mass of solute = 78.2 g; percentage decrease in elevation = 28.7 %
B. Mass of solute = 92.3 g; percentage decrease in elevation = 31.2 %
C. Mass of solute = 85.6 g; percentage decrease in elevation = 24.5 %
Correct Answer D. Mass of solute = 85.6 g; percentage decrease in elevation = 28.7 %
Correct Answer
D
Correct Option:
Mass of solute = 85.6 g; percentage decrease in elevation = 28.7 %

About This Question

This is Neco 2019 Chemistry Question 42. It is one of the objective questions from the 2019 Neco Chemistry examination.

Difficulty level: Medium .

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