Neco Model Questions Vol1 2021 Chemistry Question 31

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

Neco Model Questions Vol1 2021 Chemistry Objective / Multiple Choice Hard Difficulty
Question 31 NECO_MODEL_QUESTIONS_VOL1 • 2021 • CHEMISTRY • objective

An ore sample weighing 100 g contains 85% ZnS and 15% inert impurity. The ZnS is first roasted to ZnO with 90% efficiency, then the ZnO is reduced with carbon to metallic Zn with 80% efficiency. Alternatively, the roasted ZnO can be reduced electrolytically with a current efficiency of 95%. Assuming the same roasting efficiency for both routes, which method yields more metallic Zn and by how many grams? (Molar masses: ZnS = 97.45 g·mol⁻¹, ZnO = 81.38 g·mol⁻¹, Zn = 65.38 g·mol⁻¹).

Answer Options

A. Electrolytic reduction yields about 5.2 g more Zn than the carbon reduction method.
B. Electrolytic reduction yields about 9.1 g more Zn than the carbon reduction method.
C. Electrolytic reduction yields about 2.4 g more Zn than the carbon reduction method.
Correct Answer D. Electrolytic reduction yields about 7.7 g more Zn than the carbon reduction method.
Correct Answer
D
Correct Option:
Electrolytic reduction yields about 7.7 g more Zn than the carbon reduction method.

About This Question

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

Difficulty level: Hard .

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