Empirical Formula

Empirical Formula Quiz

Spec 3.6.2 · Oxford AQA IGCSE Chemistry: Quiz

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  1. 1. What does the empirical formula of a compound represent?

    • A. The exact number of atoms in one molecule
    • B. The simplest whole-number ratio of atoms of each element
    • C. The mass of the compound in grams
    • D. The number of moles in the compound

  2. 2. A compound has the molecular formula C4H8. What is its empirical formula?

    • A. C4H8
    • B. CH2
    • C. C2H4
    • D. CH4

  3. 3. A compound contains 4.0 g of calcium and 1.6 g of oxygen (Ar: Ca = 40, O = 16). What is its empirical formula?

    • A. CaO
    • B. CaO2
    • C. Ca2O
    • D. CaO4

  4. 4. Why can percentage composition data be used in exactly the same way as mass data when calculating empirical formula?

    • A. Because percentages are always whole numbers
    • B. Because percentages can be treated as masses in grams out of a 100 g sample
    • C. Because percentages already show mole ratios
    • D. Because percentage composition ignores oxygen

  5. 5. An empirical formula is found to be C2H5 with a relative formula mass of 29. If the actual molecular mass of the compound is 58, what is its molecular formula?

    • A. C2H5
    • B. C4H10
    • C. C6H15
    • D. C4H5

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