Balancing of Redox Reactions - Test Paper, Chemistry, class 9

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CBSE TEST PAPER 04 
CLASS XI CHEMISTRY (Redox Reactions) 
Topic  : Balancing of Redox Reactions  
   
1. Balance the following equations by oxidation number method:  
(i) CuO + NH 3  ? Cu + N 2 + H 2O  
(ii) K 2 MnO 4 + H 2O ? MnO 2 + KMnO 4 + KOH 
[4] 
2. How would you know whether a redox reaction is taking place in an acidic / 
alkaline or neutral medium?  
[1] 
3. Write the following redox reactions in the oxidation and reduction half 
reaction reactions in the oxidation and reduction half reactions. 
(i) 2K(S) + Cl 2(g) ? 2KCl (S)  
(ii) 2Al (S) +3Cu
2+
 (aq)  2Al
3+
 (aq) + 3Cu(S) 
[2] 
4. Complete the following redox reactions and balance the following equations-  
(i) Cr 2O 7
2-
 + C 2O 4
2-
  ? Cr
3+
 + CO 2 (in presence of acid)  
(ii) Sn
2+
 + Cr 2O 7
2-  
? Sn
4+
 + Cr
3+
 (in presence of acid)  
[1] 
5. Write correctly the balanced half – reaction and the overall equations for the 
following skeletal equations.  
(i)  NO 3
-
 +  Bi(S) ? Bi
3+
 + NO 2         (in acid solution) 
(ii)  Fe (OH) 2 (S) + H 2O 2 ? Fe (OH) 3(S) + H 2O    (in basic medium) 
[1]