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WorksheetsOxidation-reduction (Chemistry O-Level 5070)
Total questions: 25
Worksheet time: 19mins
Substances that lose electrons easily and are oxidized in a chemical reaction are ____________.
reducing agents
coloring agents
oxidizing agents
neutralizing agents
A camera film is covered with silver ions that darkens upon exposure to light. The reaction that
takes place is: Ag + + e‾ → Ag. In this reaction, silver ion acts as ____________
reducing agent.
dissolving agent.
analytical agent.
oxidizing agent
What is the oxidation number of Nitrogen in HNO3
-7
-5
+5
+7
Find the oxidation number of S in S2O4 2-
+3
+6
-6
-3
Which of the following statements refers to an oxidation process?
Hydrogen is added to ethene
Oxygen is removed from carbon dioxide
Chlorine accepts electrons
Increase in the oxidation number of magnesium metal
Which of these equations represents a redox reaction?
Ca(HCO3)2 → CaCO3 + H2O + CO2
CH3COOH + NaOH → CH3COONa + H2O
Zn + 2FeCl3 → ZnCl2 + 2FeCl2
NaCl + AgNO3 → AgCl + NaNO3
What are the oxidation numbers of manganese in the manganese compounds shown below?
A
B
C
D
Which of the following statements is not true when zinc powder is added to dilute hydrochloric acid?
Zinc is oxidised
Chloride ion acts as an oxidising agent
Hydrogen ion is reduced
Electrons are transferred in the reaction
Which of the following half reactions correctly represents a reduction half reaction?
Fe → Fe2+ + 2e-
Pb4+ + 2e- → Pb2+
2O-2 → O2 + 4e-
Fe + 3e- → Fe3+
An aqueous solution of potassium iodide turns from colourless to brown. What happens to the iodide ions?
Iodide ions are oxidised due to gain of electrons.
Iodide ions are oxidised due to loss of electrons.
Iodide ions are reduced due to loss of electrons.
Iodide ions are reduced due to gain of electrons.
Which of the following is NOT a redox reaction?
Displacement
Decomposition
Neutralisation
Combustion
What substance is oxidized in the following reaction?
4Fe + 3O2 → 2Fe2O3
Iron
Fluorine
Oxygen
None
What is the oxidation number of chlorine in ClO3- ?
5
1
0
2
What is the colour change of acidified KMnO4 solution when it is used as an oxidising agent?
from colourless to brown
from purple to colourless
from brown to colourless
from colourless to purple
Identify the substance that is oxidised in the reaction between carbon and zinc oxide.
C + 2ZnO → CO2 + 2Zn
C
ZnO
CO2
Zn
Identify the substance that is reduced in the reaction between copper(II) ion and magnesium.
Cu2+ + Mg → Cu + Mg2+
Cu2+
Mg
Cu
Mg2+
Identify the oxidising agent in the reaction between iron(II) chloride and zinc.
2FeCl3 + 3Zn → 2Fe + 3ZnCl2
FeCl3
Zn
Fe
ZnCl2
During which process does an atom gain one or more electrons?
transmutation
reduction
oxidation
neutralization
Which change in oxidation number indicates oxidation?
-1 to +2
-1 to -2
+2 to -3
+3 to +2
Identify the reducing agent in the reaction between sulfuric acid and zinc.
H2SO4 + Zn → H2 + ZnSO4
H2SO4
Zn
H2
ZnSO4
The oxidation numbers of all the atoms in H2SO4 must add up to
0
+5
+9
+16
Which element has been reduced?
iron oxide + lithium → iron + lithium oxide
iron
lithium
oxide
iron oxide
Given the electrochemical cell reaction:
Zn(s) + Ni2+ (aq) → Zn2+ (aq) + Ni(s)
Which species is the reducing agent?
Ni2+
Zn
Ni
Zn2+
Which reaction does not involve either oxidation or reduction?
CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
Cu2+(aq) + Zn(s) → Cu(s) + Zn2+(aq)
CuO(s) + H2SO4(aq) → CuSO4(aq) + H2O(l)
Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g)
