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Worksheetsredox f4 2022
Total questions: 40
Worksheet time: 58mins
NAME
MATRIC NUMBER
Oxidation is the _________ of electrons.
loss
gain
sharing
transfer
Choose all the statements which contain correct definitions of reduction
the removal of oxygen
the removal of hydrogen
the removal of electrons
the decrease in oxidation state
Mg → Mg2+ + 2e–
4Fe + 3O2 --> 2Fe2O3
Choose all the statements which are correct for an oxidising agent.
removes hydrogen
gains oxygen
is reduced at the end of the reaction
accepts electrons
In the reaction, Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(g)
carbon monoxide is reduced
carbon monoxide is the oxidising agent
iron(III) oxide is oxidised
iron(III) oxide is the oxidising agent
which element, if any, is oxidized?
In which of the following reactions is the underlined substance reduced?
Cl2 + 2I– –> 2Cl- + I2
Zn + H2SO4 –> ZnSO4 + H2
Fe2+ + H2O2 –> Fe3+ + H2O
CuO + H2 –> Cu + H2O
Which statement is true about oxidizing agents?
Hint: oxidizing agents are themselves reduced. Hence, they ....... electrons.
Their oxidation state is zero
They are easily oxidized
They never contain hydrogen
They readily accept electrons
Define oxidising agent and reducing agent correctly. Tick 2 correct answers
Oxidising agent is substance which oxidises another substance during a redox reaction.
Reducing agent is substance which reduces another substance during a redox reaction.
In simple word
Oxidising agents are reduced. KMnO4 and K2Cr2O7
Reducing agents are oxidised. KI.
Oxidising agent is substance which reduces another substance during a redox reaction.
Reducing agent is substance which oxidises another substance during a redox reaction.
In simple word
Oxidising agents are oxidised. KI.
Reducing agents are reduced. KMnO4 and K2Cr2O7
What is the oxidation number of manganese is MnO4-
+2
+4
+7
+8
Electron conduction is due to flow of
Protons
Electrons
Neutrons
Ions
cathode is the electrode where
reduction takes place
oxidation takes place
either reduction or oxidation
none of these
A chemical species in an electrochemical reaction that LOSSES electrons undergoes _________.
Oxidation Reaction
Reduction Reaction
If a copper sample containing some zinc impurity is to be purified by electrolysis, the anode and the cathode must be which of the following?
Pure copper anode & pure zinc cathode
Pure zinc anode & pure copper cathode
Pure copper anode & impure copper cathode
Impure copper anode & pure copper cathode
What is oxidation number of O2 ?
What is oxidation number of Cr in CrO42-?
Which electrode would have an item (key/necklace/spoon) that would be plated and gain mass?
cathode
anode
In a redox reaction, the oxidizing agent will
lose electrons and be reduced
lose electrons and be oxidized
gain electrons and be reduced
gain electrons and be oxidized
Electrons always flow from
cathode to anode
anode to cathode
Oxidation occurs at the
anode
cathode
Electrons are gained at the
anode
cathode
Diagram shows an electrolysis cell.
Which of the substances cause the bulb to light up when electricity passes through it?
Ethanol
Dilute ethanoic acid
Solid lead(II) bromide
Tetrachloromethane
What are the products formed at the anode and the cathode during the electrolysis of molten magnesium oxide using carbon electrodes?
Anode: Oxygen
Cathode: Magnesium
Anode: Magnesium
Cathode: Oxygen
Anode: Hydrogen
Cathode: Oxygen
Anode: Oxygen
Cathode: Hydrogen
Diagram shows the electrolysis of concentrated copper(II) chloride solution using carbon as electrodes.
Which of the followings is the correct half equations represents the reactions at the anode?
4OH- → 2H2O + O2 + 4e
2Cl- → Cl2 + 2e
Cu → Cu2+ + 2e
Cu2+ + 2e → Cu
Diagram
shows the apparatus set-up for the electrolysis of 1.0 mol dm -3 sodium chloride solution using carbon electrodes.Which of the following are the observation for the electrolysis process shown in Diagram?
Grey solid deposited on electrode B
Colourless gas is released at electrode B
Carbon electrode A becomes thinner
Greenish yellow gas is released at electrode A
Molten X is electrolysed using carbon electrodes. After 10 minutes, a brown solid is deposited on the cathode and a brown gas is released at the anode. What is molten X?
Lead(II) chloride
Lead(II) bromide
Copper(II) chloride
Copper(II) bromide
Table shows the results of the electrolysis of molten lead (II) bromide.
The ammeter only shows reading when solid lead (II) bromide, PbBr2 is completely melted. Which of the following explains the observation?
Bromide ions receive electrons to form bromine gas
Lead (II) ions donate electrons to produce lead metal
In the solid state, bromide and lead (II) ions are in fixed position
Electrical conductivity occurs throughout
the whole experiment
Diagram shows an electrolysis of dilute sulphuric acid.
What could be gas X and the half-equation occurring at the cathode?
Carbon dioxide, C + O2 → CO2
Hydrogen, 2H+ + 2e —>H2
Oxygen, 4OH- → H2O + O2 + 4e-
Sulphur dioxide, SO4 2- → SO2 + O2 + 2e-
What is the oxidation state of nitrogen in NH4+?
+1
-3
0
+3
In the reaction 2H2 + O2 → 2H2O, which substance is oxidized?
H2
O2
H2O
None of the above
Which of the following statements is true regarding reduction?
It is synonymous with oxidation
It always occurs at the anode
It involves the gain of electrons
It involves the loss of electrons
