Percentage Composition

Percentage Composition Quiz

Spec 3.6.2 · Oxford AQA IGCSE Chemistry: Quiz

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5 questions, one answer each

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  1. 1. What does percentage composition tell you about a compound?

    • A. The number of moles present
    • B. The proportion, by mass, of each element in the compound
    • C. The physical state of the compound
    • D. The rate at which the compound reacts

  2. 2. Which equation correctly calculates the percentage by mass of an element in a compound?

    • A. % = Mr ÷ Ar × 100
    • B. % = (Ar × number of atoms) ÷ Mr × 100
    • C. % = Ar ÷ number of atoms × 100
    • D. % = Mr × number of atoms ÷ Ar

  3. 3. What is the percentage by mass of carbon in methane, CH4 (Ar: C = 12, H = 1)?

    • A. 12%
    • B. 25%
    • C. 75%
    • D. 88%

  4. 4. In the formula Al2(SO4)3, how many oxygen atoms should be used in a percentage composition calculation?

    • A. 3
    • B. 4
    • C. 6
    • D. 12

  5. 5. A company wants to extract iron from ore as cheaply as possible. Ore A is Fe2O3 and Ore B is Fe3O4 (Ar: Fe = 56, O = 16). Based on percentage composition of iron, which ore is the better source, and why?

    • A. Ore A, because it has a higher percentage of iron by mass
    • B. Ore B, because it has a higher percentage of iron by mass
    • C. They are identical, because both contain iron and oxygen only
    • D. Neither, because percentage composition cannot be used to compare ores

Quiz