Oxidation and Reduction

Question

Reduction is defined as :

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Selected	Possible Answer
	Gain of electrons
	Loss of protons
	Increase in positive valency
	Decrease in negative valency

Question

$Co(s) + Cu^{2+}\;(aq)\rightarrow Co^{2+}(aq) + Cu(s).$ The above reaction is :

Possible Answers

Selected	Possible Answer
	Redox reaction
	Reduction reaction
	None of these
	Oxidation reaction

Question

Which of the following reactions depict the oxidising behavior of H_2SO_4 :

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Selected	Possible Answer
	$2HI + H_2SO_4\rightarrow I_2 + SO_2 + 2H_2O$
	$2NaOH + H_2SO_4\rightarrow Na_2SO_4 + 2H_2O$
	$NaCl + H_2SO_4\rightarrow NaHSO_4 + HCl$
	$2PCl_5 + H_2SO_4\rightarrow 2POCl_3 + 2HCl + SO_2Cl_2$

Question

In $C + H_2O\rightarrow CO + H_2, H_2O$ acts as :

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	None
	Reducing agent
	Both
	Oxidising agent

Question

Reducing agent is that :

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	Which takes electrons
	Which takes protons
	Which donates protons
	Which donates electrons

Question

and

reduce sulphuric acid. HCl

can reduce KMnO_4

and

can reduce :

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	None of these

Question

The compound which gives oxygen on moderate heating is :

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	Mercuric oxide
	Ferric oxide
	Aluminium oxide
	Zinc oxide

Question

In a reaction between zinc and iodine in which zinc iodide is formed, what is being oxidised :

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Selected	Possible Answer
	Zinc ions
	Zinc atom
	Iodine
	Iodide ions

Question

In the following reactions : $4P + 3KOH + 3H_2O\rightarrow 3KH_2PO_2 + PH_3$

Possible Answers

Selected	Possible Answer
	Only phosphorus is reduced
	Only phosphorus is oxidized
	Phosphorus is neither oxidized nor reduced
	Phosphorus is both oxidized and reduced

Question

The reaction of $Zn^{++} + 2e^-\rightarrow Zn$ is an example of :

Possible Answers

Selected	Possible Answer
	Redox reaction
	Oxidation
	Reduction
	None

Question

In the reaction $3Cl_2 + 6OH^-\rightarrow 5Cl^- + ClO_3^- + 3H_2O$ chlorine is :

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Selected	Possible Answer
	Neither oxidised nor reduced
	Oxidised as well as reduced
	Reduced
	Oxidised

Question

In the reaction $3Br_2 + 6CO_3^{2-} + 3H_2O\rightarrow 5Br^- + BrO_3^- + 6HCO_3^-$

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Selected	Possible Answer
	Bromine is neither reduced nor oxidised
	Bromine is both reduced and oxidised
	Bromine is oxidised and carbonate is reduced
	Bromine is reduced and water is oxidised

Question

A gas X bleaches a flower by reduction and another gas Y by oxidation these gases are, respectively

Possible Answers

Selected	Possible Answer
	$NH_3 \And SO_3$
	$NO_2 \And N_2O_5$
	$SO_2 \And Cl_2$
	$SO_2 \And PCl_3$

Question

What will happen when copper rod is dipped in aluminium nitrate solution, if the electropositive properties are as follows : Al< Zn > Cu > Ag

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Selected	Possible Answer
	Copper aluminium alloy will be formed
	Aluminium will get deposited on the rod
	No reaction will occur
	Colour of the solution will becomes blue

Question

For the reaction : $4Fe + 3O_2 \rightarrow 4Fe^{3+} + 6O^{2-}$ which of the following is a wrong statement ?

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Selected	Possible Answer
	Metallic iron is a reducing agent
	It is an example of redox reaction
	Metallic iron reduces to $Fe^{3+}$
	Fe is oxidised

Question

In the reaction

$MnO_4 ^{-} + NO_2 ^{-} \rightarrow NO_3 ^{-} + Mn^{2+}$

one mole of $MnO_4 ^{-}$ oxidises___ moles of $NO_2 ^{-}$

Possible Answers

Selected	Possible Answer
	3
	3/2
	5/2
	5

Question

In the following equation $ClO_3 ^{-} + 6H^{+} + X$ $\rightarrow Cl^{-} + 3H_2O$ , then X is

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	$6e^{-}$
	$5e^{-}$

Question

Which one of the following compounds can act as an oxidising as well as reducing agent -

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Question

When acidic solution of ferrous ammonium sulphate is treated with potassium permanganate solution then the ion which is oxidised is -

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Selected	Possible Answer

	$MnO_{4} ^{-}$
	$SO_4 ^{2-}$
	$Fe^{2+}$

Question

The violent reaction between sodium and water is an example of -

Possible Answers

Selected	Possible Answer
	Redox reaction
	Neutralization
	Reduction
	Oxidation

Question

In the formation of Pb(NO_3)_2 form $PbO_{2-}$

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Selected	Possible Answer
	is oxidised
	is both oxidised and reduced.
	is neither oxidised nor reduced
	is reduced

Question

Which of the following s an example of reduction -

Possible Answers

Selected	Possible Answer
	$[Fe(CN)_6]^{4-}$ $\rightarrow$ $[Fe(CN)_6] ^{3-}$
	$KI \rightarrow I_2$
	$H_2S \rightarrow S$
	$CuO \rightarrow Cu_2O$

Question

Reaction [Ag(NH_3)_2]^+ + $2H^+ \rightarrow$ $Ag^+ + 2NH_4 ^{+}$ is an example of -

Possible Answers

Selected	Possible Answer
	Oxidation and reduction both
	Neither oxidation nor reduction
	Oxidation
	Reduction

Question

Which of the following reactions involves neither oxidation nor reduction -

Possible Answers

Selected	Possible Answer
	$VO^{2+}$ $\rightarrow$
	$Cr^{-}$ $\rightarrow$
	$CrO_4 ^{2-}$ $\rightarrow$ $Cr_2O_7 ^{2-}$
	$2S_2O_3 ^{2-}$ $\rightarrow$ $S_4O_6 ^{2-}$

Question

What would happen when a small quantity of H_2O_2 is added to a solution of $FeSO_{4-}$

Possible Answers

Selected	Possible Answer
	is evolved
	An electron is added to $Fe^{++}$
	An electron is lost by $Fe^{++}$
	Colour disappears

Question

The reaction $2TiCl_3 \rightarrow$ TiCl_2 + TiCl_4 example of -

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Selected	Possible Answer
	reversible reaction
	dissociation
	disproportionation
	exothermic reaction

Question

The anodic reaction in the electrolysis of the aqueous solution of $NaCl is -$

Possible Answers

Selected	Possible Answer
	Oxidation of sodium ion.
	Oxidation of chloride ion
	reduction of chloride ion
	Evolution of oxygen

Question

In the reaction -

2FeCl_3 + H_2S

$\rightarrow$ 2FeCl_2 + 2HCl + S

Possible Answers

Selected	Possible Answer
	is used as an oxidant.
	and both are oxidised.
	is used as an oxidant.
	is oxidised and is reduced.

Question

A compound contains atoms X, Y and Z the oxidation number of X is + 2, Y is + 5 and Z is – 2 therefore a possible formula of the compound is :

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Question

The atomic number of an element which shows the oxidation state of + 3 is :

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	17
	32
	33
	13

Question

Which of the following is the correct oxidation number of phosphorus in Mg_2P_2O_7 :

Possible Answers

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	+ 2
	– 3
	+ 5
	+ 3

Question

Oxidation number of sulphur in Na_2SO_4 is :

Possible Answers

Selected	Possible Answer
	+ 2
	– 2
	+ 6
	– 6

Question

Oxidation state of O_2 in H_2O_2 is :

Possible Answers

Selected	Possible Answer
	+ 2
	– 2
	+ 1
	– 1

Question

If three electrons are lost by a metal ion $M^{3+}$ , its final oxidation number should be :

Possible Answers

Selected	Possible Answer
	+ 4
	+ 6
	+ 2
	0

Question

Oxidation number of in K_3[Fe(CN)_6] is :

Possible Answers

Selected	Possible Answer
	+ 2
	+ 3
	+ 1
	+ 4

Question

Oxidation number of sulphur in S_2Cl_2 is :

Possible Answers

Selected	Possible Answer
	+ 6
	– 1
	0
	+ 1

Question

Oxidation number of sulphur in $S_2O_2 ^{2-}$ is :

Possible Answers

Selected	Possible Answer
	+ 6
	– 2
	+ 1
	0

Question

Oxidation number of nitrogen in NH_3 is :

Possible Answers

Selected	Possible Answer
	– 3
	0
	+ 3
	+ 5

Question

The oxidation number of nitrogen in NH_2OH is :

Possible Answers

Selected	Possible Answer
	– 1
	– 2
	+ 1
	– 3

Question

Oxidation number of P in KH_2PO_2 is :

Possible Answers

Selected	Possible Answer
	7
	4
	6
	+1

Question

In the compounds KMnO_4 and K_2Cr_2O_7 , the highest oxidation state is of the element :

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Selected	Possible Answer
	Chromium
	Manganese
	Oxygen
	Potassium

Question

The normal oxidation state of an element is – 2. The number of electrons in its outermost shell will be

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Selected	Possible Answer
	2
	4
	6
	8

Question

Oxidation number of in Ni(CO)_4 is :

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Selected	Possible Answer
	4
	8
	2
	0

Question

Which of the following halogens always shows only one oxidation state ?

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	Br
	Cl
	F
	I

Question

In which of the following compound oxidation number of Cl is + 3 ?

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	$ClO_3 ^{-}$

Question

The oxidation number of cobalt in $[Co(CN)_6]^{3-}$ is -

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Selected	Possible Answer
	+ 3
	- 6
	+ 6
	- 3

Question

In which of the following compound oxidation number of iron is not +3

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Question

The oxidation number of in MnC_2O_4 is -

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Selected	Possible Answer
	+ 8/3
	+2
	+1
	+3

Question

The correct oxidation number of phosphorus in magnesium pyrophosphate [Mg_2P_2O_7] is -

Possible Answers

Selected	Possible Answer
	+ 3
	+ 5
	+ 2
	- 3

Question

Oxidation number of sulphur in H_2SO_5 is -

Possible Answers

Selected	Possible Answer
	+ 4
	+ 2
	+ 8
	+ 6

Question

In which of the following compound, iodine is in its highest oxidation state -

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Selected	Possible Answer

Question

Oxidation number of chlorine in Hypochlorous acid is–

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	+ 2
	zero
	+ 1
	–1

Question

The compound in which oxidation state of metal is zero -

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	All of the above

Question

The oxidation state of phosphorus is + 3 in -

Possible Answers

Selected	Possible Answer
	Metaphosphoric acid
	Orthophosphorous acid
	Orthophosphoric acid
	Pyrophosphoric acid

Question

Which of the following is a true statement -

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Selected	Possible Answer
	Oxidation state of oxygen in HOF is zero.
	Oxidation state of fluorine in HOF is – 1.
	All of the above.
	Oxidation state of chlorine in HOCl is + 1.

Question

The following reaction is used in the extraction of chromium from its ore

2Fe_2O_3.Cr_2O_3

$\rightarrow$ 2Fe_2O_3 + 4Na_2CrO_4 + 4CO_2

What is true about the oxidation states of the substance in the reaction -

Possible Answers

Selected	Possible Answer
	Carbon is oxidised from + 3 to + 4 oxidation state
	Iron is reduced from + 3 to + 2 oxidation state.
	There is no change in the oxidation states of the substances.
	Chromium is oxidised from + 3 to + 6 oxidation state.

Question

Oxidation state of nitrogen is incorrectly given for -
A-Compounds =

$NH_2OH \qquad \operatorname{Oxidation} states=-1$

B-Compounds =

$(N_2H_5)_2SO_4 \qquad \operatorname{Oxidation} states=+2$
C-Compounds =

$Mg_3N_2 \qquad \operatorname{Oxidation} states=-3$
D-Compounds =

$[Co(NH_3)_5Cl]Cl_2 \qquad \operatorname{Oxidation} states=-3$

Possible Answers

Selected	Possible Answer
	A
	B
	C
	D

Question

Out of the following acids which has different oxidation state of phosphorus as compared to others -

Possible Answers

Selected	Possible Answer
	Metaphosphoric acid
	Phosphorous acid
	Pyrophosphoric acid
	Orthophosphoric acid

Question

The brown ring complex compound is formulated as $[Fe(H_2O)_5NO^{+}]SO_4$ . The oxidation state of iron is -

Possible Answers

Selected	Possible Answer
	1
	3
	zero
	2

Question

When KMnO_4 is reduced with oxalic acid in acidic solution, the oxidation number of Mn changes from -

Possible Answers

Selected	Possible Answer
	7 to 2
	4 to 2
	7 to 4
	6 to 4

Question

The oxidation number of each sulphur in Na_2S_4O_6 is -

Possible Answers

Selected	Possible Answer
	2 and 4 (three S have + 2 and one S has + 4)
	2.5
	5 and 0 (two S have + 5 and the other S have 0)
	2 and 3 (two S have + 2 and the other two have + 3)

Question

In a triatomic molecule the oxidation states of atoms A, B and C are + 6, + 1 and – 2 respectively. The molecular formula of the compound will be -

Possible Answers

Selected	Possible Answer

	None of the above

	Both of the above.

Question

Which of the following statements is not correct -

Possible Answers

Selected	Possible Answer
	Two mole of electrons are used in the reduction of $MnO_4 ^{-}$ to $MnO_3 ^{-}$
	The oxidation number increases in the process of reduction.
	Three electrons per chromium atom are used in the reduction of dichromate by Fe (II)
	The oxidation state of oxygen is $-\frac{1}{2}$ in potassium superoxide.

Question

The oxidation number of nitrogen in NH_4NO_3 is :

Possible Answers

Selected	Possible Answer
	+ 3
	+ 5
	– 3 and + 5
	+ 3 and + 5

Question

In acidic medium, reaction : $MnO_4 ^{-}\rightleftharpoons Mn^{2+}$ is an example of :

Possible Answers

Selected	Possible Answer
	Reduction by five electrons
	Reduction by three electrons
	Oxidation by three electrons
	Oxidation by five electrons

Question

In which of the following reaction there is no change in valency

Possible Answers

Selected	Possible Answer
	$4KClO_3 \rightarrow$
	$BaO_2 + H_2SO_4 \rightarrow$
	$2BaO + O_2 \rightarrow$
	$SO_2 + 2H_2S \rightarrow$

Question

In the reaction : $BaO_2 + H_2SO_4 \rightarrow$ BaSO_4 + H_2SO_4

Possible Answers

Selected	Possible Answer
	Valency of barium increases
	Valency of barium is not changed
	Valency of barium decreases
	Valency of barium becomes zero

Question

A balanced half reaction for the unbalanced whole reaction

$CrO_4 ^{-2} + SO_3 ^{-2}$ $\rightarrow CrO_2 ^{-} + SO_4 ^{-2} + OH^{-}$

Possible Answers

Selected	Possible Answer
	$2CrO_4^{-2} + 8H_2O + 6e$ $\rightarrow$ $2CrO_2 ^{-} + 4H_2O + 8OH^{-}$
	$CrO_4 ^{-2} + H_2O \rightarrow$ $CrO_2 ^{-} + H_2O + OH^{-}$
	$2CrO_4^{-2} + 8H_2O \rightarrow CrO_2 ^{-} + 4H_2O + 8OH^{-}$
	$3CrO_4 ^{-2} + 4H_2O + 6e \rightarrow$ $2CrO_2 ^{-} + 8OH^{-}$

Question

Choose the set of the coefficient that correctly balance the equation

$xCr_2O_7 ^{-2} + yH^{+} + ze$ $\rightarrow aCr^{+3} + bH_2O$

Possible Answers

Selected	Possible Answer

Question

$8Al + 3Fe_3O_4 \rightarrow$ 4Al_2O_3 + 9Fe

In the reaction how many total electrons will be transferred

Possible Answers

Selected	Possible Answer
	24
	20
	12
	14

Question

How many protons will be added to the right to balance the process $MnO_4 ^{-} \rightarrow$ $Mn^{+2}$

Possible Answers

Selected	Possible Answer
	5
	8
	0
	2

Question

Reactions (a and b)
(a):- $Fe^{+3} + H_2O_2 \rightarrow$ $Fe^{+2} + O_2$

(b):- $Cr(OH)_2 + I_2 \rightarrow$ $Cr(OH)_3 + 2I^{-}$

Should be balanced in acidic or basic medium

Possible Answers

Selected	Possible Answer
	a (basic), b (basic)
	a (acidic), b (acidic)
	a (acidic), b (basic)
	a (basic), b (acidic)

Question

In the reaction, $A_2 ^{-n} + xe \rightarrow A _1 ^{-n}$
Here x will be

Possible Answers

Selected	Possible Answer

Question

$PbS + H_2O_2 \rightarrow PbSO_4 + 4H_2O$

The coefficient of the reactants in the balanced state of the equation are

Possible Answers

Selected	Possible Answer
	2, 4
	1, 3
	2, 2
	1, 4

Question

In acidic medium equivalent weight of K_2Cr_2O_7 (molecular weight = M) is :

Possible Answers

Selected	Possible Answer
	M / 6
	M / 3
	M / 4
	M / 2

Question

In the following reaction

$As_2S_5 + NO_3 ^{-} \rightarrow$ $AsO_4 ^{3-} + SO_4 ^{2-} + NO_2$

The equivalent weight of As_2S_5

is

Possible Answers

Selected	Possible Answer
	M/6
	M/30
	M/40
	M/8

Question

In a reaction the equivalent weight of KMnO_4 becomes one third of its molecular weight. The oxidation state of in the final product is

Possible Answers

Selected	Possible Answer
	+ 6
	+ 3
	+ 4
	+ 2

Question

The equivalent weight of reducing agent in the reaction

$2[Fe(CN)_6]^{3-} + 2OH^{-} + H_2O_2$ $\rightarrow 2[Fe(CN)_6]^{4-}$ $+ 2H_2O + O^{-}$

Possible Answers

Selected	Possible Answer
	6/8
	16
	212
	17

Question

In a redox reaction K_2Cr_2O_7 changes to Cr_2(SO_4)_3 . If the molecular weight of is M and equivalent weight E then -

Possible Answers

Selected	Possible Answer
	M = 3E
	M = 6E
	E = 6M
	E = 2M

Question

is oxidised to Fe_2O_3

. If the molecular weight of Fe_3O_4

is M and equivalent weight E then -

Possible Answers

Selected	Possible Answer
	E=3/3M
	E=3/2M
	E=M/3
	E = M

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