Neco Model Questions Vol1 2020 Chemistry Question 18

Practice objective / multiple choice question 18 from the 2020 Neco Model Questions Vol1 Chemistry examination.

Neco Model Questions Vol1 2020 Chemistry Objective / Multiple Choice Hard Difficulty
Question 18 NECO_MODEL_QUESTIONS_VOL1 • 2020 • CHEMISTRY • objective

A 1.00 g sample of impure white phosphorus (P₄) containing 90 % P₄ by mass is burnt completely in excess O₂. The calorimeter records a heat release of 2.90 kJ for the sample. (i) Determine the heat released per mole of pure P₄. (ii) Using the reaction \( \text{P}_4 + 5\text{O}_2 \rightarrow \text{P}_4\text{O}_{10} \), calculate the standard enthalpy of formation of \( \text{P}_4\text{O}_{10}(s) \). (iii) State whether the formation of \( \text{P}_4\text{O}_{10} \) is exothermic or endothermic.

Answer Options

A. -450 kJ·mol⁻¹ (exothermic)
Correct Answer B. -399 kJ·mol⁻¹ (exothermic)
C. -350 kJ·mol⁻¹ (exothermic)
D. -399 kJ·mol⁻¹ (endothermic)
Correct Answer
B
Correct Option:
-399 kJ·mol⁻¹ (exothermic)

About This Question

This is Neco Model Questions Vol1 2020 Chemistry Question 18. It is one of the objective questions from the 2020 Neco Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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