Redox Reactions

Thiosulphate reacts differently with iodine and bromine in the reactions given below: 2S2O32- + I2 S4O62- + 2I- S2O32- + 5Br2 + 5H2O 2SO42- + 4Br- + 10H+ Which of the following statements justifies the above dual behaviour of thiosulphate?

1. Thiosulphate undergoes oxidation by bromine and reduction by iodine in these reactions
2. Bromine is a weaker oxidant than iodine
3. Bromine is a stronger oxidant than iodine
4. Bromine undergoes oxidation and iodine undergoes reduction in these reactions

Match List I with List II. Choose the correct answer from the options given below :

1. A-IV, B-I, C-II, D-III
2. A-I, B-II, C-III, D-IV
3. A-II, B-III, C-IV, D-I
4. A-III, B-II, C-I, D-IV

Only 2 mL of KMnO4 solution of unknown molarity is required to reach the end point of a titration of 20 mL of oxalic acid (2M) in acidic medium. The molarity of KMnO4 solution should be M.

Which of the following reactions are disproportionation reactions? Choose the correct answer from the options given below :

1. (A), (B)
2. (A), (D)
3. (B), (C), (D)
4. (A), (B), (C)

The lowest oxidation number of an atom in a compound A2B is -2 . The number of electrons in its valence shell is .

Given below are two statements: In the light of the above statements, choose the most appropriate answer from the options given below :

1. Statement I is correct but statement II is incorrect
2. Both statement I and statement II are incorrect
3. Statement I is incorrect but statement II is correct
4. Both statement I and statement II are correct

Number of moles of H+ ions required by 1 mole of MnO4- to oxidise oxalate ion to CO2 is .

2MnO4- + bI- + cH2O xI2 + yMnO2 + zOH- If the above equation is balanced with integer coefficients, the value of z is .

Total number of species from the following which can undergo disproportionation reaction is . H2O2, ClO3-, P4, Cl2, Ag, Cu+1, F2, NO2, K+

Chlorine undergoes disproportionation in alkaline medium as shown below : aCl2(g) + bOH-(aq) cClO-(aq) + dCl-(aq) + eH2O(l) The values of a, b, c and d in a balanced redox reaction are respectively :

1. 3, 4, 4 and 2
2. 1, 2, 1 and 1
3. 2, 4, 1 and 3
4. 2, 2, 1 and 3