When SO2 is passed through acidified solution of potassium dichromate, then chromium sulphate is formed. The change in oxidation number of chromium is:

(1) +4 to+2 

(2) +5 to+3

(3) +6 to+3

(4) +7 to+2

Subtopic:  Oxidizing & Reducing Agents |
 81%
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In the reaction;

2Ag + 2H2SOAg2SO4 + 2H2O + SO2,H2SO4 acts as:

(1) oxidising agent

(2) reducing agent

(3) dehydrating agent

(4) none of these

Subtopic:  Balancing of Equations |
 77%
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In the equation,

NO2- +  H2NO3- + 2H+ + ne-

n stands for:

(a) H+

(b) e-

(c) 2e-

(d) 3e-

Subtopic:  Oxidizing & Reducing Agents |
 78%
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In the reaction between acidified K2Cr2O7 and iron (II) ions shown by the equation:

Cr2O72-(aq) + 6Fe2+(aq) +14H+(aq)2Cr3+(aq) + 7H2O(l) + 6Fe3+(aq)

(a) the colour of the solution changes from green to blue

(b) the iron (II) ions are reduced 

(c) the dichromate ions are reduced 

(d) hydrogen ions are reduced

Subtopic:  Oxidizing & Reducing Agents |
 81%
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Which metal exhibits more than one oxidation states?

(1) Na

(2) Mg

(3) Al

(4) Fe

Subtopic:  Introduction to Redox and Oxidation Number |
 89%
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In which iron has the lowest oxidation state?

(a) Fe(CO)5

(b) Fe2O

(c) K4Fe(CN)6

(d) FeSO4.(NH4)2SO4.6H2O

Subtopic:  Oxidizing & Reducing Agents |
 88%
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When an acidified solution of ferrous ammonium sulphate is treated with KMnO4 solution, the ion which is oxidised is:

(a) Fe2+

(b) SO42-

(c) NH4+

(d) MnO4-

 

Subtopic:  Oxidizing & Reducing Agents | Redox Titration & Type of Redox |
 75%
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In the reaction,

2Na2S2O+ I Na2S4O6 + 2NaI,

the oxidation state of sulphur is:

(1) decreased

(2) increased

(3) unchanged

(4) none of these

Subtopic:  Oxidizing & Reducing Agents |
 81%
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During a redox change, the oxidant K2Cr2O7 is always reduced to:

(1) Cr5+

(2) Cr4+

(3) Cr3+

(4) Cr2+

Subtopic:  Introduction to Redox and Oxidation Number |
 88%
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Which is not a redox change?

(a) CaCO3 CaO + CO2

(b) 2H2 + O2 2H2O

(c) Na + H2 NaOH + 1/2 H2

(d) MnCl3  MnCl2 + 1/2 Cl2

Subtopic:  Introduction to Redox and Oxidation Number |
 71%
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