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Answer it the way your examiner marks it.

Type any exam question. You get the command word decoded, a model answer split into the marking points your board credits, the words examiners look for, and where students usually lose marks. Every answer draws on Salam Academy's own lessons, board notes and past-paper questions.

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Example answer
Cambridge 9701explain3 marks

Explain why the boiling points of the halogens increase down Group 17.

What earns the marks

“explain” means: give the reason, linking structure to the property: say what changes and why it raises the boiling point.

Three linked points: the molecules get bigger, so the instantaneous dipole–induced dipole (London) forces get stronger, so more energy is needed to separate the molecules.

Model answer, point by point
  1. 1
    Down the group the molecules have more electrons (they are larger).
    1
  2. 2
    So the instantaneous dipole–induced dipole forces between molecules are stronger.
    1
  3. 3
    So more energy is needed to overcome these forces between molecules, giving a higher boiling point.
    1
Words the examiner looks for
more electronsinstantaneous dipole–induced dipolebetween moleculesmore energy to overcome
Exam technique
  • Say “between molecules”: the forces broken on boiling are intermolecular, not covalent bonds.
  • Each point should lead to the next; use “so” or “therefore”.
Where marks are lost
  • Saying covalent bonds break when halogens boil.
  • Writing “stronger bonds” without saying which forces.
  • Mentioning only molecular mass with no link to the forces.

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