Igcse Model Questions Vol1 2023 Chemistry Question 3

Practice objective / multiple choice question 3 from the 2023 Igcse Model Questions Vol1 Chemistry examination.

Igcse Model Questions Vol1 2023 Chemistry Objective / Multiple Choice Medium Difficulty
Question 3 IGCSE_MODEL_QUESTIONS_VOL1 • 2023 • CHEMISTRY • objective

The molecular formula \(\mathrm{C_5H_{12}}\) can represent three structural isomers: n‑pentane, 2‑methylbutane and 2,2‑dimethylpropane. Their standard heats of combustion are 3500 kJ mol\(^{-1}\) for n‑pentane, 3520 kJ mol\(^{-1}\) for 2‑methylbutane and 3550 kJ mol\(^{-1}\) for 2,2‑dimethylpropane. (i) State how many structural isomers \(\mathrm{C_5H_{12}}\) has. (ii) Which isomer releases the greatest amount of energy on complete combustion? Using the data, calculate the total energy released when 2.0 mol of this isomer is burnt completely.

Answer Options

Correct Answer A. 3 isomers; 2,2‑dimethylpropane releases the most energy; total energy = 7100 kJ
B. 3 isomers; 2‑methylbutane releases the most energy; total energy = 7200 kJ
C. 3 isomers; n‑pentane releases the most energy; total energy = 7000 kJ
D. 2 isomers; 2,2‑dimethylpropane releases the most energy; total energy = 7100 kJ
Correct Answer
A
Correct Option:
3 isomers; 2,2‑dimethylpropane releases the most energy; total energy = 7100 kJ

About This Question

This is Igcse Model Questions Vol1 2023 Chemistry Question 3. It is one of the objective questions from the 2023 Igcse Model Questions Vol1 Chemistry examination.

Difficulty level: Medium .

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