CBSE Questions for Class 11 Medical Chemistry Redox Reactions Quiz 11 - MCQExams.com

When $$MnO_{2}$$ is fused with $$KOH$$, a coloured compound is formed. The product and its colour are, respectively :
  • $$K_{2}MnO_{4}$$, purple green
  • $$KMnO_{4}$$, purple
  • $$Mn_{2}O_{3}$$, brown
  • $$Mn_{3}O_{4}$$, black
Identity the pair of binary corresponds in which nitrogen exhibits the lowest and the highest oxidation state.
  • $$NH_{3}$$, $$NO_{2}$$
  • $$NH_3$$, $$N_{2}O_{5}$$
  • $$N_{2}$$, $$HNO_{3}$$
  • $$N_{2}O$$, $$N_{2}O_{5}$$
Number of moles of acidic $$KMnO_4$$ needed for complete oxidation of $$1$$ mole equimolar mixture of $$FeSO_4$$ and $$FeC_2O_4$$ is:
  • $$\dfrac {2}{5}$$
  • $$\dfrac {1}{5}$$
  • $$\dfrac {1}{10}$$
  • none of the above
Amongst the following, identify the species with an atom in $$+6$$ oxidation state.
  • $$[MnO_4]^-$$
  • $$[Cr(CN)_6]^{3-}$$
  • $$Cr_2O_3$$
  • $$CrO_2Cl_2$$
The average oxidation states of sulphur in $$Na_2S_2O_3$$ and $$Na_2S_4O_6$$ are, respectively :
  • $$+5$$ and $$+2$$
  • $$+2$$ and $$+2.5$$
  • $$+5$$ and $$2.5$$
  • $$+2$$ and $$+4$$
Which of the following does not exist?
  • HS$$_6$$
  • HPO$$_4$$
  • FeI$$_3$$
  • HClO$$_4$$
In a daniel cell, if $$A(E^o = -0.76 \ C)$$ and $$B(E^o = -2.36 \ V)$$ half cells are taken then:
  • $$B$$ acts as anode
  • $$A$$ acts as anode
  • $$B$$ acts as cathode
  • cannot be predicted
 How many substances have underlined atoms of different nature?
$$Na_2\underline{S_4}O_6,Na_2\underline{S_2}O_3,CaO\underline{Cl_2},\underline{N_2}H_4O_3,\underline{Fe_3}O_4,K\underline{I_3},Cr\underline{O_5},K_2\underline{Cr_2}O_7$$
  • 7
  • 5
  • 4
  • 8
Oxidation state of  'S' in sodium tetrathionate is :
  • $$+5,0,0,+5$$
  • $$+6,+6,0$$
  • $$+4,+2,+5$$
  • $$+2,0,+2, +3$$
In an experiment, $$50$$ mL of $$0.1$$ M solution of a metallic salt reacted exactly with $$25$$ mL of $$0.1$$ M solution of sodium sulphite. In the reaction, $${SO_3}^{-}$$ is oxidised to $${SO_4}^{2-}$$. If the original oxidation number of the metal in the salt was $$3$$, what would be the new oxidation number of the metal?
  • 0
  • 1
  • 2.5
  • 4
The oxidation state of the most electronegative element in the products of the reaction between $$BaO_2$$ and $$H_2SO_4$$ is:
  • 0 and -1
  • -1 and -2
  • -2 and 0
  • -2 and +1
The oxidation state of +3 for phosphorous is in :
  • hypophosphorous acie
  • meta-phosphoric acid
  • ortho-phosphoric acid
  • phosphorous acid
In which of the following, sulphur has the highest oxidation state?
  • $$SO_2$$
  • $$SO_3$$
  • $$H_2SO_4$$
  • $$H_2S$$
Which of the following is/are correct in case of Mohr's salt?
  • It decolourises $$KMnO_4$$.
  • It is primary standard titrant.
  • It is a double salt.
  • Oxidation state of Fe is +3 in the salt.
Which does not represent auto-redox process?
  • $$4CrO_5 + 6H_2SO_4 \rightarrow 2Cr_2(SO_4)_3+6H_2O+7O_2$$
  • $$2C_6H_5CHO \overset{Al(OC_2H_5)_3}{\rightarrow}C_6H_5COOCH_2C_6H_5$$
  • $$4KCIO_3\rightarrow 3KClO_4+KCI$$
  • $$CHO-CHO \xrightarrow {NaOH} CH_2OH-CHO + COOH-CHO$$

Select the incorrect statement for developing of an exposed camera film involving the reaction.
175651_a29f0ce1bc1e4f1b891347d849a55fa6.png
  • Hydroquinol acts as reductant.
  • $$Ag^+$$ acts as oxidant.
  • Hydroquinol and AgBr undergoes redox change.
  • It involves intramolecular change.
Which of the following statement(s) is/are true?
  • All reactions are oxidation and reduction reactions.
  • Oxidising agent is itself reduced.
  • Oxidation and reduction always go side by side.
  • Oxidation number during reduction decreases.
Choose the correct statement(s).
  • If oxidation and reduction is carried out simultaneously in one container, the redox reactions are called direct redox changes.
  • If oxidation and reduction is carried out simultaneously in two compartments, the redox reactions are called indirect redox changes.
  • Direct redox changes produce electrical energy.
  • Indirect redox changes produce electrical energy.
Which of the following is/are redox reactions?
  • $$BaO_2+H_2SO_4 \rightarrow BaSO_4+ H_2O_2$$
  • $$2BaO+O_2 \rightarrow 2BaO_2$$
  • $$2KClO_3 \rightarrow 2KCl+ 3O_2$$
  • $$SO_2 + 2H_2S \rightarrow 2H_2O+ 3S$$
The oxidation number of sulphur in $$S_8, S_2F_2$$ and $$H_2S$$ respectively, are :
  • $$0,\: +1$$ and $$-2$$
  • $$+2,\: +1$$ and $$-2$$
  • $$0,\: +1$$ and $$+2$$
  • $$-2,\: +1$$ and $$-2$$
Oxidation number of $$Cr$$ is $$+5$$ in :
  • $${ K }_{ 3 }Cr{ O }_{ 8 }$$
  • $${ \left( { NH }_{ 3 } \right) }_{ 3 }Cr{ O }_{ 4 }$$
  • $${ K }_{ 2 }Cr{ O }_{ 4 }$$
  • $$\left[ Cr{ \left( { NH }_{ 3 } \right) }_{ 5 }\left( { H }_{ 2 }O \right) \right] { Cl }_{ 3 }$$
Consider the following unbalanced reactions:
$$I: Zn+dil.\:{ H }_{ 2 }S{ O }_{ 4 }\longrightarrow ZnS{ O }_{ 4 }+{ H }_{ 2 }$$
$$II: Zn+conc.\:{ H }_{ 2 }S{ O }_{ 4 }\longrightarrow ZnS{ O }_{ 4 }+S{ O }_{ 2 }+{ H }_{ 2 }O\quad $$
$$III: Zn+HN{ O }_{ 3 }\longrightarrow Zn{ \left( { NO }_{ 3 } \right)  }_{ 2 }+{ NH }_{ 4 }{ NO }_{ 3 }+{ H }_{ 2 }O$$
Oxidation number of hydrogen changes in :
  • $$I,II,III$$
  • $$I,II$$
  • $$II,III$$
  • $$I$$
The complex $${ \left[ Fe{ \left( { H }_{ 2 }O \right)  }_{ 5 }NO \right]  }^{ 2+ }$$ is formed in the ring-test for nitrate when freshly prepared $$FeS{ O }_{ 4 }$$ solution is added to aqueous solution of $$N{ O }_{ 3 }^{ - }$$ followed by addition of conc. $${ H }_{ 2 }S{ O }_{ 4 }$$. This complex is formed by charge transfer in which :
  • $${ Fe }^{ 2+ }$$ changes to $${ Fe }^{ 3+ }$$ and $${NO}^{+}$$ changes to $$NO$$
  • $${ Fe }^{ 2+ }$$ changes to $${ Fe }^{ 3+ }$$ and $$NO$$ changes to $${NO}^{+}$$
  • $${ Fe }^{ 2+ }$$ changes to $${ Fe }^{ + }$$ and $$NO$$ changes to $${NO}^{+}$$
  • no charge transfer takes place
Which combination appears odd with respect to oxidation number per atom of the underlined?
  • $${ H }_{ 2 }\underline { S } { O }_{ 5 },{ H }_{ 2 }\underline { S } { O }_{ 8 },{ K }_{ 2 }\underline { { Cr }_{ 2 } } { O }_{ 7 }$$
  • $$\underline { Cr } { O }_{ 5 },\underline { Cr } { O }_{ 4 }^{ 2- },S{ O }_{ 4 }^{ 2- }$$
  • Both (a) and (b)
  • None of the above
Of the following acids, the one that is strongest is :
  • $$HBr{O}_{4}$$
  • $$HOCl$$
  • $$H{NO}_{2}$$
  • $${H}_{3}{PO}_{3}$$
For a titration of $$100\: {cm}^{3}$$ of $$0.1$$ $$M$$ $${ Sn }^{ 2+ }$$ to $${ Sn }^{ 4+ }$$, $$50$$ $${cm}^{3}$$ of $$0.40$$ $$M$$ $${ Ce }^{ 4+ }$$ solution was required. The oxidation state of cerium in the reduction product is :
  • $$+1$$
  • $$+2$$
  • $$+3$$
  • $$0$$
$$1$$ mole of $${ N }_{ 2 }{ H }_{ 4 }$$ loses $$10$$ mol of electrons to form a new compound $$Y$$. Assuming that all the nitrogen appear in the new compound, what is the oxidation state of nitrogen in $$Y$$ (no change in the oxidation state $$H$$)?
  • $$-1$$
  • $$-3$$
  • $$+3$$
  • $$+5$$
Which statement(s) is/are not correct about the reaction?

$$H_{2}O_2(aq) + 2I^- (aq) + 2H^+(aq) \rightarrow I_2(aq) + 2H_2O(l) I_2(aq) + 2Na_2S_2O_3\rightarrow Na_2S_4O_6+2NaI?$$
  • The $$I_2$$ formed is consumed completely in the second state is confirmed by addition of starch just before its complete consumption
  • The reaction process is called clock reaction because the appearance of blue colour on addition of starch is like an alarm given by clock
  • Sulphur is oxidised whereas iodine is oxidised and reduced during whole process
  • $$H_2O_2$$ acts as reducing agent
$$Mn{O}_{4}^{2-}$$ (1 mole) in neutral aqueous medium disproportionate to :
  • $$2/3$$ mole $${Mn}{O}_{4}^{-}$$ and $$1/3$$ mole $$Mn{O}_{2}$$
  • $$1/3$$ mole $${Mn}{O}_{4}^{-}$$ and $$2/3$$ mole $$Mn{O}_{2}$$
  • $$1/3$$ mole of $${Mn}_{2}{O}_{7}$$ and $$1/3$$ mole of $$Mn{O}_{2}$$
  • $$2/3$$ mole of $${Mn}_{2}{O}_{7}$$ and $$1/3$$ mole of $$Mn{O}_{2}$$
Compound(s) of $$Cu$$ and $$Ag$$ showing $$+3$$ oxidation state is\are :
  • $$K_3 [CuF_6] $$
  • $$Na[AgF_4]]$$
  • both a and b
  • none of these
Quinhydrone half cell is not reversible to:
  • H$$^+$$
  • quinone
  • quinol
  • OH$$^-$$
Find the oxidation number of elements in each case :

$$ S$$ in $$Na_2S_2O_3$$,  $$S_4$$,  $$S_8$$ and $$Na_2S_2O_7$$.
  • $$+2,\: 0,\: 0,\: +6$$
  • $$+1,\: 0,\: +1,\: +6$$
  • $$+1,\: 0,\: 0,\: +4$$
  • None of the above
The coefficients of $$I^{-}, IO_{3}^{-}$$ and $$H^{+}$$ in the redox reaction,

$$I^{-}+ IO_{3}^{-}+H^{+}\longrightarrow I_{2}+H_{2}O$$

in the balanced form respectively are
  • $$5,1,6$$
  • $$1,5,6$$
  • $$6,1,5$$
  • $$5,6,1$$
Out of $$\underset { (I) }{ { H }_{ 2 }S{ O }_{ 4 } } ,\ \underset { (II) }{ { H }_{ 2 }{ S }_{ 2 }{ O }_{ 7 } } ,\ \underset { (III) }{ { H }_{ 2 }S{ O }_{ 5 } }$$ and $$\underset { (IV) }{ { H }_{ 2 }{ S }_{ 2 }{ O }_{ 3 } } $$ :
  • oxidation number of sulphur is $$+6$$ in all except $$IV$$
  • peroxy linkage is in $$I,II$$ and $$III$$
  • peroxy linkage is in $$II$$ and $$III$$
  • oxidation number of sulphur is $$-2$$ in $$I$$ and $$IV$$
In which of the following pairs is there the greatest difference in the oxidation number of the underlined elements?
  • $$\underline { N } { O }_{ 2 }$$ and $$\underline { { N }_{ 2 } } { O }_{ 4 }$$
  • $$\underline { S } { O }_{ 3 }^{ 2- }$$ and $$\underline { S } { O }_{ 4 }^{ 2- }$$
  • $$\underline { { S }^{ 2- } } $$ and $$\underline { S } { O }_{ 3 }^{ 2- }$$
  • $$\underline { { S }^{ 2- } } $$ and $$\underline { S } { O }_{ 4 }^{ 2- }$$
What is the oxidation number of the underlined elements?
a.  $${ H }_{ 2 }\underline { S }$$                b.  $${ H }_{ 2 }\underline { S } { O }_{ 4 }$$                 c.  $${ Na }_{ 2 }\underline { { S }_{ 2 } } O_3$$                   d.  $${ Na }_{ 2 }\underline { { S }_{ 4 } } { O }_{ 6 }$$              

  • a. -2, b. +6,  c. +2,  d. +2.5 
  • a. -2,  b. +4,  c. +2,  d. +2.5 
  • a. -2,  b. +6,  c. +3,  d. +2.5
  • None of these
Which of the following represent redox reactions?
I.   $${ Cr }_{ 2 }{ O }_{ 7 }^{ 2- }+2\overset { \ominus  }{ O } H\longrightarrow 2Cr{ O }_{ 4 }^{ 2- }+{ H }_{ 2 }O$$
II.  $$Zn+CuS{ O }_{ 4 }\longrightarrow ZnS{ O }_{ 4 }+Cu$$
III. $$2Mn{ O }_{ 4 }^{ \ominus  }+3{ Mn }^{ 2+ }+4\overset { \ominus  }{ O } H\longrightarrow 5Mn{ O }_{ 2 }+2{ H }_{ 2 }O$$
IV. $$2{ Cu }^{ \oplus  }\longrightarrow Cu+{ Cu }^{ 2+ }$$
  • I, II
  • I, III
  • III, IV
  • II, III, IV
In the compound $$Y{ Ba }_{ 2 }{ Cu }_{ 3 }{ O }_{ 7 }$$ which shows superconductivity, what is the oxidation state of $$Cu$$?
Assume that the rare earth element yttrium is in its usual +3 oxidation state.
  • $$+\displaystyle\frac{7}{3}$$
  • $$-\displaystyle\frac{7}{3}$$
  • $$\displaystyle\frac{5}{3}$$
  • $$-\displaystyle\frac{5}{3}$$
In which of the following cases is the oxidation state of $$N$$ atom wrongly calculated?
  • $$\begin{matrix} Compound & Oxidation\quad state \\ N{ H }_{ 4 }Cl & -3 \end{matrix}$$
  • $$\begin{matrix} Compound & Oxidation\quad state \\ { \left( { N }_{ 2 }{ H }_{ 5 } \right) }_{ 2 }S{ O }_{ 4 } & +2 \end{matrix}$$
  • $$\begin{matrix} Compound & Oxidation\quad state \\ { Mg }_{ 3 }{ N }_{ 2 } & -3 \end{matrix}$$
  • $$\begin{matrix} Compound & Oxidation\quad state \\ NH_{ 2 }OH & -1 \end{matrix}$$
The oxidation number of $$Cr$$ is $$+6$$ in :
  • $$Fe{ Cr }_{ 2 }{ O }_{ 4 }$$
  • $$KCr{ O }_{ 3 }Cl$$
  • $$Cr{ O }_{ 5 }$$
  • $${ \left[ Cr{ \left( OH \right) }_{ 4 } \right] }^{ \ominus }$$
Which of the following has/have been arranged in order of decreasing oxidation number of sulphur?
  • $${ H }_{ 2 }{ S }_{ 2 }{ O }_{ 7 }>{ Na }_{ 2 }{ S }_{ 4 }{ O }_{ 6 }>{ Na }_{ 2 }{ S }_{ 2 }{ O }_{ 3 }>{ S }_{ 8 }$$
  • $$S{ O }^{ 2+ }>S{ O }_{ 4 }^{ 2- }>S{ O }_{ 3 }^{ 2- }>HS{ O }_{ 4 }^{ \ominus }$$
  • $${ H }_{ 2 }S{ O }_{ 5 }>{ H }_{ 2 }S{ O }_{ 3 }>S{ Cl }_{ 2 }>{ H }_{ 2 }S$$
  • $${ H }_{ 2 }S{ O }_{ 4 }>S{ O }_{ 2 }>{ H }_{ 2 }S>{ H }_{ 2 }{ S }_{ 2 }{ O }_{ 8 }$$
What is the oxidation number of tungsten in the ion $$W_6O_6Cl^{2-}_{12}$$ ? 
  • 2.7
  • 3.3
  • 3.7
  • 4.3
It required $$40.05$$ mL of $$\displaystyle 1 M \:Ce^{4+}$$ to titrate $$20$$ mL of $$\displaystyle 1 M \:Sn^{2+}$$ to $$\displaystyle Sn^{4+}$$. What is the oxidation state of the cerium in the product?
  • $$+1$$
  • $$+2$$
  • $$0$$
  • $$+3$$
Which one of the following statements is/are not correct?
  • Oxidation number of $$S$$ in $$(NH_4)_2S_2O_8$$ is $$+7$$.
  • Oxidation number of $$Os$$ in $$OsO_4$$ is $$+8$$.
  • Oxidation number of $$S$$ in $$H_2SO_5$$ is $$+8$$.
  • Oxidation number of $$O$$ in $$KO_2$$ is $$+\frac{1}{2}$$.
Oxidation state of phosphorus in the $$PH_4^+ ,PO_2^{3-}, PO_4^{3-}$$ and $$PO_3^{3-}$$ respectively, are :
  • $$-4, \:+1,\: +3,\: +5$$
  • $$-3,\: +3,\: +5,\: +1$$
  • $$+3,\: -3,\: +5,\: +1$$
  • $$-3,\: +1,\: +5,\: +3$$
The oxidation state of oxygen of $$H_2O_2$$ in the final products when it reacts with $$As_2O_3$$ is :
  • $$0$$
  • $$1$$
  • $$-1$$
  • $$-2$$
Which of the following does not represent redox reaction?
  • $$Cr_2O^{2-}_7+2\overset{\circleddash}{O}H\rightarrow CrO^{2-}_4+H_2O$$
  • $$SO^{2-}_5+2I^{\circleddash}+2H^{\bigoplus}\rightarrow I_2+SO^{2-}_4$$
  • $$2Ca(OH)_2+2Cl_2\rightarrow Ca(ClO)_2+CaCl_2+2H_2O$$
  • $$PCl_5\rightarrow PCl_3+Cl_2$$
The oxidation state of oxygen of $$H_2O_2$$ in the final products when it reacts with $$ClO^{\circleddash}_3$$ is :
  • $$0$$
  • $$1$$
  • $$-1$$
  • $$-2$$
In the reaction $$SO_2+\frac{1}{2}O_2\xrightarrow [  ]{V_2O_5}SO_3$$, the vanadium changes from $$V^{5+}$$ to:
  • $$V^{4+}$$
  • $$V^{6+}$$
  • $$V^{3+}$$
  • $$V^{2+}$$
Consider a galvanic cell using solid $$Cu$$ and $$Fe$$ metals with their corresponding solutions.
What is the $$E^{\circ}_{cell}$$?
Standard Potential (V)Reduction Half-Reaction
$$2.87$$$$F_{2}(g) + 2e^{-} \rightarrow 2F^{-}(aq)$$
$$1.51$$$$MnO_{4}^{-}(aq) + 8H^{+}(aq) + 5e^{-}\rightarrow Mn^{2+}(aq) + 4H_{2}O(l)$$
$$1.36$$$$Cl_{2}(aq) + 3e^{-} \rightarrow 2Cl^{-}(aq)$$
$$1.33$$$$Cr_{2}O_{7}^{2-} (aq) + 14H^{+}(aq) + 6e^{-} \rightarrow 2Cr^{3+}(aq) + 7H_{2}O(l)$$
$$1.23$$$$O_{2}(g) + 4H^{+}(aq) + 4e^{-}\rightarrow 2H_{2}O(l)$$
$$1.06$$$$Br_{2}(l) + 2e^{-} \rightarrow 2Br^{-}(aq)$$
$$0.96$$$$NO_{3}^{-}(aq) + 4H^{+}(aq) + 3e^{-}\rightarrow NO(g) + H_{2}O(l)$$
$$0.80$$$$Ag^{+}(aq) + e^{-} \rightarrow Ag(s)$$$
$$0.77$$$$Fe^{3+} (aq) + e^{-} \rightarrow Fe^{2+}(aq)$$
$$0.68$$$$O_{2}(g) + 2H^{+}(aq) + 2e^{-}\rightarrow H_{2}O_{2}(aq)$$
$$0.59$$$$MnO_{4}^{-}(aq) + 2H_{2}O(l) + 3e^{-}\rightarrow MnO_{2}(s) + 4OH^{-}(aq)$$
$$0.54$$$$I_{2}(s) + 2e^{-}\rightarrow 2I^{-}(aq)$$
$$0.40$$$$O_{2}(g) + 2H_{2}O(l) + 4e^{-} \rightarrow 4OH^{-}(aq)$$
$$0.34$$$$Cu^{2+}(aq) + 2e^{-} \rightarrow Cu(s)$$
$$0$$$$2H^{+}(aq) + 2e^{-}\rightarrow H_{2}(g)$$
$$-0.28$$$$Ni^{2+}(aq) + 2e^{-}\rightarrow Ni(s)$$
$$-0.44$$$$Fe^{2+}(aq) + 2e^{-}\rightarrow Fe(s)$$
$$-0.76$$$$Zn^{2+}(aq) + 2e^{-}\rightarrow Zn(s)$$
$$-0.83$$$$2H_{2}O(l) + 2e^{-}\rightarrow H_{2}(g) + 2OH^{-}(aq)$$
$$1.66$$$$Al^{3+}(aq) + 3e^{-}\rightarrow Al(s)$$
$$-2.71$$$$Na^{+}(aq) + e^{-} \rightarrow Na(s)$$
$$-3.05$$$$Li^{+}(aq) + e^{-}\rightarrow Li(s)$$
  • $$-0.78 V$$
  • $$0.10 V$$
  • $$0.78 V$$
  • $$-0.10 V$$
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