Neco Model Questions Vol1 2025 Chemistry Question 49

Practice objective / multiple choice question 49 from the 2025 Neco Model Questions Vol1 Chemistry examination.

Neco Model Questions Vol1 2025 Chemistry Objective / Multiple Choice Medium Difficulty
Question 49 NECO_MODEL_QUESTIONS_VOL1 • 2025 • CHEMISTRY • objective

Two structural isomers of the hydrocarbon \(C_{5}H_{12}\) - n‑pentane and isopentane - are each burnt completely in excess oxygen. In a 2.00 L calorimeter of heat capacity 2.5 kJ °C⁻¹, 1.00 g of each isomer is combusted. The temperature rise recorded is 3.2 °C for n‑pentane and 2.8 °C for isopentane. Determine the molar heat of combustion (ΔcH) for each isomer and state which releases more energy per mole.

Answer Options

Correct Answer A. n‑pentane: -5.78×10² kJ mol⁻¹; isopentane: -5.05×10² kJ mol⁻¹; n‑pentane releases more per mole
B. n‑pentane: -5.78×10² kJ mol⁻¹; isopentane: -5.05×10² kJ mol⁻¹; isopentane releases more per mole
C. n‑pentane: -5.50×10² kJ mol⁻¹; isopentane: -5.05×10² kJ mol⁻¹; n‑pentane releases more per mole
D. n‑pentane: -5.78×10² kJ mol⁻¹; isopentane: -5.30×10² kJ mol⁻¹; isopentane releases more per mole
Correct Answer
A
Correct Option:
n‑pentane: -5.78×10² kJ mol⁻¹; isopentane: -5.05×10² kJ mol⁻¹; n‑pentane releases more per mole

About This Question

This is Neco Model Questions Vol1 2025 Chemistry Question 49. It is one of the objective questions from the 2025 Neco Model Questions Vol1 Chemistry examination.

Difficulty level: Medium .

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