Q.1
What substance is oxidized in the following reaction?4Fe + 3O2 --> 2Fe2O3
  • Iron
  • Fluorine
  • Oxygen
  • None of these
Q.2
Determine the oxidation number of chromium in CrO42-.
  • 5
  • 6
  • 4
  • 2
Q.3
A decrease in oxidation number.
  • Oxidation
  • combination
  • reduction
  • All of above
Q.4
Substance that oxidizes another substance by accepting its electrons.
  • oxidising agent
  • reducing agent
  • combustion
  • None of these
Q.5
In which substance does sulfur have a negative oxidation number?
  • Na2S
  • SO2
  • S
  • Both A & B
Q.6
The oxidation number of Hydrogen in KH potassium hydride equals:
  • -1
  • +1
  • 0
  • 2
Q.7
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
Q.8
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.
Q.9
Which of the following is the balanced half -reaction for the oxidation of Cu to Cu+2?
  • Cu --> Cu+2
  • Cu + 2 e- --> Cu+2
  • Cu - 2e- --> Cu+2
  • Cu --> Cu+2 + 2 e-
Q.10
What is the oxidation number of iodine in KIO3?
  • 5
  • 1
  • 0
  • -1
Q.11
Reduction is the ___________ of electrons.
  • loss
  • gain
  • transfer
  • share
Q.12
An element's oxidation numbers changed from zero to +2 during a reaction. What happened to that element?
  • It was oxidized
  • It was reduced
  • It was both oxidized and reduced
  • It was neither oxidized nor reduced
Q.13
If an atom lost electrons, it...
  • was burned
  • was reduced
  • was oxidized
  • it became negative
Q.14
Of the 5 types of reactions, which one(s) are oxidation-reduction?
  • all of them
  • only double replacement
  • double replacement and combustion
  • all of them except double replacement
Q.15
Which of the following is NOT an example of an oxidation reduction reaction?
  • metal rusting
  • acid neutralizing base
  • burning methane
  • photosynthesis
Q.16
Which of the following has an oxidation number of zero on the chlorine atom?
  • NaCl
  • Cl2
  • Cl-
  • ClO3-
Q.17
What is the oxidation number on the nitrogen in NO?
  • 0
  • -1
  • -2
  • +2
Q.18
What is the oxidation number on the nitrogen in Mg3N2?
  • 0
  • -2
  • -3
  • +3
Q.19
What is the oxidation number on the nitrogen in NO2-?
  • -1
  • +3
  • -3
  • +4
Q.20
An element's oxidation numbers remain the same during a reaction. What happened to that element?
  • It was oxidized
  • It was reduced
  • It was both oxidized and reduced
  • It was neither oxidized nor reduced
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