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कर्नाटक बोर्ड पी.यू.सी.पीयूसी विज्ञान इयत्ता ११

Consider the reactions: 2SX2OX3X(2−)(aq)+lX2(S)⟶SX4OX6X(2−)(aq)+2lX−(aq) SX2OX3X(2−)(aq)+2BrX2(l)+5HX2O(l)⟶2SOX4X2−(aq)+4BrX−(aq)+10HX+(aq) Why does the same reductant, thiosulphate react

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प्रश्न

Consider the reactions:

\[\ce{2S_2O_3^{(2-)}(aq) + l_2(S) -> S_4O_6^{(2-)}(aq) + 2l-(aq)}\]

\[\ce{S_2O_3^{(2-)}(aq) + 2Br_2(l) + 5H_2O(l) -> 2SO_4^{2-} (aq) + 4Br-(aq) + 10H+ (aq)}\]

Why does the same reductant, thiosulphate react differently with iodine and bromine?

संख्यात्मक
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उत्तर

The average oxidation number (O.N.) of `"S"_2"O"_3^(2-)` in is +2. Being a stronger oxidising agent than I2, Br2 oxidises `"S"_2"O"_3^(2-)` to `"SO"_4^(2-)`, in which the O.N. of S is +6. However, I2 is a weak oxidising agent. Therefore, it oxidises `"S"_2"O"_3^(2-)` to `"S"_4"O"_6^(2-)`, in which the average O.N. of S is only +2.5. As a result, `"S"_2"O"_3^(2-)` reacts differently with iodine and bromine.

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पाठ 7: Redox Reactions - EXERCISES [पृष्ठ २८१]

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एनसीईआरटी Chemistry Part 1 and 2 [English] Class 11
पाठ 7 Redox Reactions
EXERCISES | Q 8.14 | पृष्ठ २८१

संबंधित प्रश्‍न

Justify that the following reaction is redox reaction:

\[\ce{4BCl3(g) + 3LiAlH4(s) → 2B2H6(g) + 3LiCl(s) + 3 AlCl3(s)}\]


Fluorine reacts with ice and results in the change: \[\ce{H2O(s) + F2(g) → HF(g) + HOF(g)}\]

Justify that this reaction is a redox reaction.


How do you count for the following observations?

When concentrated sulphuric acid is added to an inorganic mixture containing chloride, we get colourless pungent-smelling gas HCl, but if the mixture contains bromide then we get red vapour of bromine. Why?


Identify the substance oxidised, reduced, oxidising agent and reducing agent for the following reaction:

\[\ce{2AgBr (s) + C6H6O2(aq) → 2Ag(s) + 2HBr (aq) + C6H4O2(aq)}\]


Identify the substance oxidised, reduced, oxidising agent and reducing agent for the following reaction:

\[\ce{HCHO(l) + 2[Ag (NH3)2]+(aq) + 3OH–(aq) → 2Ag(s) + HCOO–(aq) + 4NH3(aq) + 2H2O(l)}\]


Identify the substance oxidised, reduced, oxidising agent and reducing agent for the following reaction:

\[\ce{HCHO (l) + 2Cu^{2+}(aq) + 5 OH–(aq) → Cu2O(s) + HCOO–(aq) + 3H2O(l)}\]


Identify the substance oxidised, reduced, oxidising agent and reducing agent for the following reaction:

\[\ce{N2H4(l) + 2H2O2(l) → N2(g) + 4H2O(l)}\]


Identify the substance oxidised, reduced, oxidising agent and reducing agent for the following reaction:

\[\ce{Pb(s) + PbO2(s) + 2H2SO4(aq) → 2PbSO4(s) + 2H2O(l)}\]


Consider the reactions:

  1. \[\ce{H3PO2(aq) + 4 AgNO3(aq) + 2 H2O(l) → H3PO4(aq) + 4Ag(s) + 4HNO3(aq)}\]
  2. \[\ce{H3PO2(aq) + 2CuSO4(aq) + 2 H2O(l) → H3PO4(aq) + 2Cu(s) + H2SO4(aq)}\]
  3. \[\ce{C6H5CHO(l) + 2[Ag (NH3)2]+(aq) + 3OH–(aq) → C6H5COO–(aq) + 2Ag(s) + 4NH3 (aq) + 2 H2O(l)}\]
  4. \[\ce{C6H5CHO(l) + 2Cu^{2+}(aq) + 5OH–(aq) → No change observed}\]

What inference do you draw about the behaviour of Ag+ and Cu2+ from these reactions?


Which of the following is not an example of redox reaction?


Identify disproportionation reaction


Which of the following statement(s) is/are not true about the following decomposition reaction.

\[\ce{2KClO3 -> 2KCl + 3O2}\]

(i) Potassium is undergoing oxidation.

(ii) Chlorine is undergoing oxidation.

(iii) Oxygen is reduced.

(iv) None of the species are undergoing oxidation or reduction.


Identify the correct statements with reference to the given reaction.

\[\ce{P4 + 3OH- + 3H2O -> PH3 + 3H2PO^{-}2}\]

(i) Phosphorus is undergoing reduction only.

(ii) Phosphorus is undergoing oxidation only.

(iii) Phosphorus is undergoing oxidation as well as reduction.

(iv) Hydrogen is undergoing neither oxidation nor reduction.


Write redox couples involved in the reactions given.

\[\ce{Mg + Fe^{2+} -> Mg^{2+} + Fe}\]


Find out the oxidation number of chlorine in the following compounds and arrange them in increasing order of oxidation number of chlorine.

\[\ce{NaClO4, NaClO3, NaClO, KClO2, Cl2O7, ClO3, Cl2O, NaCl, Cl2 , ClO2}\].

Which oxidation state is not present in any of the above compounds?


Which of the following reactions is the metal displacement reaction? Choose the right option.


The reaction of sulphur in alkaline medium is given below:

\[\ce{S8(s) + {a} OH^-(aq) -> {b} S^{2-}(aq) + {c} S2O^{2-}3(aq) + {d} H2O(l)}\]

The values of 'a' are ______. (Integer answer)


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