Target: 10 Questions in 10 minutes

An IB Chemistry data booklet is helpful
1. The average oxidation state of sulphur in sodium thiosulphate Na2S2O3 is:
  • A.   +1
  • B.   +2
  • C.   +4
  • D.   +6
2. In which of the following compounds does oxygen have an average oxidation state of -1?
  • A.   H2O
  • B.   KO2
  • C.   Na2O2
  • D.   MgSO4

3. Which of the following statements is correct about oxidation state?

I. Oxidations states can only be calculated for ionic compounds.
II. The oxidation state is a number assigned to an atom to show the number of electrons transferred in forming a bond.
III. The oxidation state for fluorine is always -1.
  • A.   I only
  • B.   II only
  • C.   III only
  • D.   II and III only
4. Which of the following species has manganese in an oxidation state of +6?
  • A.   Mn(OH)2
  • B.   [MnO4]3-
  • C.   [HMnO4]-
  • D.   [MnO4]-
5. What is the average oxidation number of C in CH3CH2CH2COOH?
  • A.   -4
  • B.   -1
  • C.   0
  • D.   +1

6. In how many of the following compounds does the element chromium have an oxidation number of +6?

Na2CrO4 Na2Cr2O7 NaCrO2 Na2Cr2O4
  • A.   1
  • B.   2
  • C.   3
  • D.   4
7. Choose the correct name of the compound Ca(ClO)2.
  • A.   Calcium chlorate (I)
  • B.   Calcium chlorate (III)
  • C.   Calcium chlorate (IV)
  • D.   Calcium chloride
8. When the species below are arranged in the order of increasing oxidation state for nitrogen, which of the following is correct?
  • A.   NO2- < NO < N2O5 < N2O
  • B.   NO2-< N2O < NO < N2O5
  • C.   NO < N2O < N2O5 <NO2-
  • D.   N2O < NO <NO2-< N2O5

9. When SO2 reacts with Na2O, what is the correct name of the compound formed?

I. Sodium sulphite
II. Sodium sulphate (IV)
III. Sodium sulphate (VI)
  • A.   I and II only
  • B.   II and III only
  • C.   I and III only
  • D.   I, II and III
10. Which of the following compounds is correctly named?
  • A.   CO2 – carbon(II) oxide
  • B.   HClO4 – hydrogen chlorine(IV) oxide
  • C.   KMnO4 – potassium manganate(VII)
  • D.   Cu2O – copper(II) oxide