Neco Model Questions Vol1 2022 Chemistry Question 35

Practice objective / multiple choice question 35 from the 2022 Neco Model Questions Vol1 Chemistry examination.

Neco Model Questions Vol1 2022 Chemistry Objective / Multiple Choice Medium Difficulty
Question 35 NECO_MODEL_QUESTIONS_VOL1 • 2022 • CHEMISTRY • objective

A 1.00 kg sample of a gasoline mixture contains 60 % by mass of n‑octane (\(\mathrm{C_8H_{18}}\)) and 40 % by mass of iso‑octane (2,2,4‑trimethylpentane, also \(\mathrm{C_8H_{18}}\)). The standard enthalpy of combustion is -5470 kJ mol⁻¹ for n‑octane and -5475 kJ mol⁻¹ for iso‑octane. (a) Calculate the total heat released when the sample is completely combusted. (b) Determine the average molar mass of the mixture.

Answer Options

Correct Answer A. a) ≈ -4.79 × 10⁴ kJ released; b) average molar mass = 114.23 g mol⁻¹
B. a) ≈ -4.79 × 10³ kJ released; b) average molar mass = 113.00 g mol⁻¹
C. a) ≈ -5.10 × 10⁴ kJ released; b) average molar mass = 115.60 g mol⁻¹
D. a) ≈ -4.65 × 10⁴ kJ released; b) average molar mass = 112.50 g mol⁻¹
Correct Answer
A
Correct Option:
a) ≈ -4.79 × 10⁴ kJ released; b) average molar mass = 114.23 g mol⁻¹

About This Question

This is Neco Model Questions Vol1 2022 Chemistry Question 35. It is one of the objective questions from the 2022 Neco Model Questions Vol1 Chemistry examination.

Difficulty level: Medium .

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