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A-LevelChemistryChemical bondingOct/Nov 2021Paper 1 Q71 Mark

The strength of hydrogen bonding increases as the electronegativity of the element bonded to hydrogen increases. Some information for a range of hydrides is given. hydride | boiling point /K ---|--- PH3 | 185 HCl | 188 HF | 293 H2O | 373 Which statement and reason about these hydrides is correct?

AThe boiling point of PH3 is much lower than the boiling point of H2O because PH3 does not form hydrogen bonds or instantaneous dipole-induced dipole forces between its molecules.
BThe boiling point of HF is higher than the boiling point of HCl because the bond energy of H-F is greater than the bond energy of H–Cl.
CThe boiling point of H2O is higher than the boiling point of HF because each hydrogen bond between the H2O molecules is stronger than each hydrogen bond between HF molecules.
DThe boiling points of PH3 and HCl are similar because the molecules of PH3 and HCl have the same number of electrons and similar intermolecular forces.

✓ Correct Answer

The correct answer is D: The boiling points of PH3 and HCl are similar because the molecules of PH3 and HCl have the same number of electrons and similar intermolecular forces.

📋 Examiner Report & Trap Analysis

Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...

🎯 Mark Scheme Breakdown

Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.

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About This A-Level Chemistry Question

Topic

This multiple-choice question tests Chemical bonding in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Chemistry Oct/Nov 2021 examination, Paper 1 Variant 2.

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