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Redox Reactions · Question 7

NEET (UG) 2021MCQEasy📈 Topic in 25% papers+4−1
1

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

  1. 2Pb(NO3)2 2PbO + 4NO2 + O2
  2. 2KClO3 2KCl + 3O2
  3. Cr2O3 + 2Al Al2O3 + 2Cr
  4. Fe + 2HCl FeCl2 + H2

Answer

(3) Cr2O3 + 2Al Al2O3 + 2Cr

Solution

⇒ (1) and (2) are decomposition reactions.

⇒ (4) is a hydrogen displacement reaction (Fe displaces hydrogen from the acid).

⇒ In (3), Al, a more reactive metal, displaces Cr from its oxide (thermite / aluminothermic reaction).

∴ As per NCERT, Cr2O3 + 2Al Al2O3 + 2Cr is a metal displacement reaction.

Answer: (3)

NEET (UG) 2021

Keep practising — Redox Reactions

2

What is the change in oxidation number of carbon in the following reaction? CH4(g) + 4Cl2(g) CCl4(l) + 4HCl(g)

  1. 0 to +4
  2. -4 to +4
  3. 0 to -4
  4. +4 to +4
NEET (UG) 2020
3

Which of the following reactions are disproportionation reaction? Select the correct option from the following :

  1. A, C and D
  2. A and B only
  3. A and D only
  4. A, B and C
NEET (UG) 2019
4

Consider the change in oxidation state of bromine corresponding to different emf values as shown in the given diagram : BrO4- 1.82 V BrO3- 1.5 V HBrO 1.595 V Br2 1.0652 V Br- Then the species undergoing disproportionation is :

  1. BrO4-
  2. BrO3-
  3. Br2
  4. HBrO
NEET 2018
5

The correct order of N-compounds in its decreasing order of oxidation states is

  1. HNO3, NO, N2, NH4Cl
  2. HNO3, NO, NH4Cl, N2
  3. HNO3, NH4Cl, NO, N2
  4. NH4Cl, N2, NO, HNO3
NEET 2018
6

For the redox reaction, MnO4- + C2O42- + H+ Mn2+ + CO2 + H2O The correct coefficients of the reactants for the balanced equation are

  1. array|c|c|c| MnO4- & C2O42- & H+ \ 16 & 5 & 2 \ array
  2. array|c|c|c| MnO4- & C2O42- & H+ \ 2 & 5 & 16 \ array
  3. array|c|c|c| MnO4- & C2O42- & H+ \ 2 & 16 & 5 \ array
  4. array|c|c|c| MnO4- & C2O42- & H+ \ 5 & 16 & 2 \ array
NEET 2018
7

Assuming complete ionisation, same moles of which of the following compounds will require the least amount of acidified KMnO4 for complete oxidation?

  1. FeSO3
  2. FeC2O4
  3. Fe(NO2)2
  4. FeSO4
AIPMT 2015
8

Which of the following processes does not involve oxidation of iron?

  1. Formation of Fe(CO)5 from Fe.
  2. Liberation of H2 from steam by iron at high temperature.
  3. Rusting of iron sheets.
  4. Decolourisation of blue CuSO4 solution by iron.
AIPMT 2015 (Cancelled)
9

The pair of compounds that can exist together is

  1. FeCl3, SnCl2
  2. HgCl2, SnCl2
  3. FeCl2, SnCl2
  4. FeCl3, KI
AIPMT 2014
10

In acidic medium, H2O2 changes Cr2O72- to CrO5 which has two (-O-O-) bonds. Oxidation state of Cr in CrO5 is

  1. +5
  2. +3
  3. +6
  4. -10
AIPMT 2014
11

When Cl2 gas reacts with hot and concentrated sodium hydroxide solution, the oxidation number of chlorine changes from

  1. zero to +1 and zero to −5
  2. zero to −1 and zero to +5
  3. zero to −1 and zero to +3
  4. zero to +1 and zero to −3
AIPMT 2012 (Prelims)

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