NEET Chemistry Redox Reactions MCQs Set B

Question:  The number of moles of KMnO₄ that will be needed to react with one mole of sulphite ion in acidic solution is

• a) 1
• b) 3/5
• c) 4/5
• d) 2/5

Answer: 2/5

Question:  Standard reduction potentials of the half reactions are given below

The strongest oxidising and reducing agents respectively are

• a) F₂and I^– 
• b) Br₂ and Cl^– 
• c) Cl₂ and Br^– 
• d) Cl₂ and I₂

Answer: F₂and I^– 

Question:  Standard electrode potential for Sn⁴⁺ / Sn²⁺ couple is +0.15 V and that for the Cr³⁺ / Cr couple is –0.74 V. These two couples in their standard state are connected to make a cell. The cell potential will be

• a) +1.83 V
• b) +1.19 V
• c) +0.89 V
• d) +0.18 V

Answer: +0.89 V

Question: Standard reduction electrode potential of three metals X, Y and Z are –1.2 V, +0.5 V and –3.0 V respectively. The reducing power of these metals will be

• a) X > Y > Z
• b) Y > Z > X
• c) Y > X > Z
• d) Z > X > Y

Answer: Z > X > Y

Question:  In the reaction

• a) Oxygen is oxidised only
• b) Oxygen is reduced only
• c) Oxygen is neither oxidised nor reduced
• d) Oxygen is both oxidised and reduced

Answer: Oxygen is both oxidised and reduced

Question: Which change requires an oxidising agent?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  Given the following reactions involving A, B, C and D

(i) C ⁺ B⁺ → C+ + B                  (ii) A⁺ + D → No reaction

(iii) C⁺ + A → No reaction          (iv) D + B⁺ → D⁺ + B

The correct arrangement of A, B, C, D in order of their decreasing ability as reducing agent

• a) D > B > C > A
• b) A > C > D > B
• c) C > A > B > D
• d) C > A > D > B

Answer: C > A > D > B

Question: Which element undergoes disproportionation in water?

• a) Cl₂ 
• b) F₂  
• c) K
• d) Cs

Answer: Cl₂ 

Question:  Standard reduction potentials at 25°C of Li⁺ / Li, Ba²⁺ / Ba, Na⁺ / Na and Mg²⁺ / Mg are –3.05, –2.90, –2.71 and –2.37 volt respectively. Which one of the following is the strongest oxidizing agent?

• a) Ba²⁺
• b) Mg²⁺ 
• c) Na⁺
• d) Li⁺

Answer:  Mg²⁺ 

Question:  Which substance is serving as a reducing agent in the following reaction?

14H⁺ + Cr₂O₇^2– + 3Ni → 7H₂O + 3Ni²⁺ + Cr³⁺

• a) H⁺  
• b) Cr₂O₇^2– 
• c) H₂O 
• d) Ni

Answer: Ni

Question:  Oxidation state of Fe in Fe₃O₄  is

• a) 5/4
• b) 4/5
• c) 3/2
• d) 8/3

Answer: 8/3

More Questions........................................................

Question: The oxide, which cannot act as a reducing agent, is

• a) CO₂
• b) ClO₂
• c) NO₂ 
• d) SO₂

Answer:  CO₂

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

• a) A₂(BC₂)₂  
• b) A₃(BC₄)₂
• c) A₂(BC₃)₂ 
• d) A₃(B₂C)₂

Answer:  A₃(BC₄)₂

Question:  The oxidation states of sulphur in the anions SO₃^2–, S₂O₄^2– and S₂O₆^2– follow the order

• a) S₂O₄^2– < SO₃^2– < S₂O₆^2– 
• b) SO₃^2– < S₂O₄^2– < S₂O₆^2–
• c) S₂O₄^2– < S₂O₆^2– < SO₃^2– 
• d) S₂O₆^2– < S₂O₄^2– < SO₃^2–

Answer:  S₂O₄^2– < SO₃^2– < S₂O₆^2– 

Question:  Electrode potential for the following half-cell reactions are

The EMF for the cell reaction Fe²⁺ + Zn → Zn²⁺ + Fe will be

• a) – 0.32 V
• b) + 1.20 V
• c) – 1.20 V
• d) + 0.32 V

Answer: + 0.32 V

Question:  In acidic medium, H₂O₂ changes  bonds. Oxidation state of Cr in CrO₅ is

• a) +5
• b) +3
• c) +6
• d) –10

Answer: +6

Question: Standard reduction electrode potential of three metals X, Y and Z are –1.2 V, +0.5 V and –3.0 V respectively. The reducing power of these metals will be

• a) X > Y > Z
• b) Y > Z > X
• c) Y > X > Z
• d) Z > X > Y

Answer: Z > X > Y

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

• a) N₃H 
• b) NH₂OH
• c) N₂H₄
• d) NH₃

Answer:  N₃H 

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

• a) Liberation of H₂ from steam by iron at high temperature
• b) Rusting of iron sheets
• c) Decolourization of blue CuSO₄ solution by iron
• d) Formation of Fe(CO)₅ from Fe

Answer:  Formation of Fe(CO)₅ from Fe

Question:  The number of moles of H₂O₂ required to completely react with 400 ml of 0.5 N KMnO₄ in acidic medium are

• a) 0.1
• b) 0.2
• c) 1.0
• d) 0.5

Answer: 0.1

Question: When benzaldehyde is oxidised to give benzoic acid then the oxidation state of carbon of aldehydic group is changed from

• a) +2 to +3
• b) +1 to +3
• c) Zero to +2
• d) No change

Answer: +1 to +3

Question: Which of the following is incorrect regarding salt bridge solution?

• a) Solution must be a strong electrolyte
• b) Solution should be inert towards both electrodes
• c) Size of cations and anions of salt should be much different
• d) Salt bridge solution is prepared in gelatin or agar-agar to make it semi-solid

Answer: Size of cations and anions of salt should be much different

Question: The average oxidation state of chlorine in bleaching powder is

• a) –1
• b) +1
• c) Zero
• d) –2 as well as +2

Answer: Zero

Question: Which compound acts as oxidising agent only?

• a) SO₂
• b) H₂S 
• c) H₂SO₄
• d) HNO₂

Answer:  H₂SO₄

Question:  In case of CH₃COOH, the oxidation number of carbon of carboxylic group is

• a) –3
• b) Zero
• c) +1
• d) +3

Answer: +3

Question: When an alkali metal is reacted with hydrogen then metallic hydride is formed. In this reaction

• a) Hydrogen is oxidised
• b) Hydrogen is reduced
• c) Hydrogen is neither oxidised nor reduced
• d) Hydrogen is oxidised as well as reduced

Answer: Hydrogen is reduced

Question: Three metals A, B and C are arranged in increasing order of standard reduction electrode potential, hence their chemical reactivity order will be

• a) A < B < C
• b) A > B > C
• c) B > C > A
• d) A = B = C

Answer: A > B > C

Question:  Number of electrons involved in the reaction when 0.1 mol NH₃ dissolved in water

• a) 2
• b) 0.4
• c) 0.9
• d) Zero

Answer: Zero

Question: Electrode potential depends upon

• a) Size of electrode
• b) Surface area of electrode
• c) Temperature
• d) Shape of electrode

Answer: Temperature

Question: In the process of photosynthesis, which takes place in green plants which undergoes reduction?

• a) Water
• b) CO₂
• c) Protons
• d) Photons

Answer:  CO₂