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Redox Reactions · Question 18

AIPMT 2012 (Prelims)MCQMedium📈 Topic in 25% papers+4−1
1

A mixture of potassium chlorate, oxalic acid and sulphuric acid is heated. During the reaction which element undergoes maximum change in the oxidation number?

  1. S
  2. H
  3. Cl
  4. C

Answer

(3) Cl

Solution

Potassium chlorate (oxidant) oxidises oxalic acid to CO2 in acid medium:

KClO3+3H2C2O4 KCl+6CO2+3H2O

Cl: +5 (in KClO3) → −1 (in KCl) change = 6

C: +3 (in H2C2O4) → +4 (in CO2) change = 1

S stays +6 and H stays +1.

Chlorine shows the maximum change in oxidation number.

Answer: (3)

AIPMT 2012 (Prelims)

Keep practising — Redox Reactions

2

In which of the following compounds, nitrogen exhibits highest oxidation state?

  1. N2H4
  2. NH3
  3. N3H
  4. NH2OH
AIPMT 2012 (Prelims)
3

Oxidation numbers of P in PO43-, of S in SO42- and that of Cr in Cr2O72- are respectively

  1. +3, +6 and +5
  2. +5, +3 and +6
  3. –3, +6 and +6
  4. +5, +6 and +6
AIPMT 2009
4

Number of moles of MnO4- required to oxidize one mole of ferrous oxalate completely in acidic medium will be

  1. 7.5 moles
  2. 0.2 moles
  3. 0.6 moles
  4. 0.4 moles
AIPMT 2008
5

Which is the best description of the behaviour of bromine in the reaction given below? H2O + Br2 HOBr + HBr

  1. Proton acceptor only
  2. Both oxidised and reduced
  3. Oxidised only
  4. Reduced only
AIPMT 2004
6

The oxidation states of sulphur in the anions SO32-, S2O42- and S2O62- follow the order

  1. S2O42- < SO32- < S2O62-
  2. SO32- < S2O42- < S2O62-
  3. S2O42- < S2O62- < SO32-
  4. S2O62- < S2O42- < SO32-
AIPMT 2003
7

Which reaction is not feasible?

  1. 2KI + Br2 2KBr + I2
  2. 2KBr + I2 2KI + Br2
  3. 2KBr + Cl2 2KCl + Br2
  4. 2H2O + 2F2 4HF + O2
AIPMT 2002
8

Oxidation numbers of A, B, C are +2, +5 and -2 respectively. Possible formula of compound is

  1. A2(BC2)2
  2. A3(BC4)2
  3. A2(BC3)2
  4. A3(B2C)2
AIPMT 2000

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