CAIE A Level Chemistry 9701 · Atoms, molecules and stoichiometry
Sulfur has a relative atomic mass of 32.06. A sample of the element contains several isotopes, including sulfur-32 and sulfur-34. Elemental sulfur exists as molecules with the formula .
Explain what is meant by each of the following terms.
(i) the unified atomic mass unit
(ii) the relative atomic mass, Ar, of sulfur
(iii) the relative isotopic mass of sulfur-34
(iv) the relative molecular mass, Mr, of
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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