Redox Reactions NEET Questions

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Redox Reactions Chemistry NEET Practice Questions

1 / 59

Which of the following is an example of a redox reaction that is also a combustion reaction?

2H₂ + O₂ → 2H₂O

2Na + Cl₂ → 2NaCl

CH₄ + 2O₂ → CO₂ + 2H₂O

2Na + 2H₂O → 2NaOH + H₂

2 / 59

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

(b) Both oxidized and reduced

(d) Reduced only

(a) Proton acceptor only

3 / 59

Which of the following is an example of a redox reaction where the oxidation number of sulfur changes?

d) SO₃ + H₂O ---------> H₂SO₄

b) S + 2H₂O ---------> H₂SO₃ + 2H₂

a) H₂SO₄ + 2NaOH ---------> Na₂SO₄ + 2H₂O

c) SO₂ + 2H₂S ---------> 2H₂O + 3S

4 / 59

In the following reaction

Cr(OH)₃ + OH^– + IO₃---------- > CrO₄^{2 –} + H₂O + I^–

(d) all are true

(b) Cr(OH)₃ is oxidized

(a) IO₃^– is an oxidizing agent

5 / 59

What is the oxidation state of phosphorus in H₃PO₄?

-5

-4

6 / 59

What is the oxidation state of nitrogen in ammonia, NH₃?

-2

-3

7 / 59

What is the oxidation state of chlorine in sodium hypochlorite, NaClO?

-2

-1

8 / 59

Which of the following is a reducing agent?

H₂SO₄

CuSO₄

Cl₂

9 / 59

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

(a) S

(b) H

(d) C

10 / 59

Which reaction is not feasible?

(b) 2KBr + I₂ ----------- > 2KI + Br₂

(d) 2H₂O + 2F₂ ----------- > 4HF + O₂

(a) 2KI + Br₂ ----------- >2KBr + I₂

11 / 59

Given E° (Fe2+/ Fe) = – 0.44 V and E° (Fe³⁺/ Fe²⁺) =0.77 V Fe²⁺, Fe³⁺ and Fe are placed together then

(d) Fe₂⁺ decreases

(a) Fe³⁺ increases

(b) Fe³⁺ decreases

12 / 59

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–

(d) S₂O₆^2– < S₂O₄^2– < SO3^2–

(b) SO₃^2– < S₂O₄^2– < S₂O₆^2–

13 / 59

Which of the following is redox reaction?

(a) Evaporation of H₂O

(d) In atmosphere O₃ from O₂ by lightning

(b) Both oxidation and reduction

14 / 59

In the following reaction 4P + 3KOH + 3H₂O ------------- > 3KH₂PO₂ + PH3

(b) P is only reduced

(a) P is only oxidized

(d) none of these

15 / 59

The oxidation state of I in H₄IO₆^– is

(d) + 5

(a) + 1

(b) – 1

16 / 59

In electrolysis of NaCl, when Pt electrode is taken then H2 is liberated at cathode, while with Hg cathode it forms sodium amalgam because

(b) more voltage is required to reduce H+ at Hg than at Pt

(d) the concentration of H+ ions is larger when Pt electrode is taken.

(a) Hg is more inert than Pt

17 / 59

The most convenient method to protect the bottom of ship made of iron is

(d) connecting it with Pb block

(b) white tin plating

(a) coating it with red lead oxide

18 / 59

Which of the following is an example of a redox reaction where oxidation and reduction occur simultaneously?

c) 2H₂O -------- > 2H₂ + O₂

a) Mg + 2HCl -------- > MgCl₂ + H₂

b) 2AgNO₃ + Cu -------- > Cu(NO₃)₂ + 2Ag

d) 2FeSO₄ + H₂SO₄ + H₂O₂ -------- > Fe₂(SO₄)₃ + 2H₂O

19 / 59

What is the oxidation state of sulfur in H₂SO₄?

-6

-4

20 / 59

What does "redox" stand for?

Reducible-oxidizable

Reduction-oxidation

Reductase-oxidase

Reductive-oxidative

21 / 59

In the reaction Zn + CuSO₄ → ZnSO₄ + Cu, which species is being oxidized?

CuSO₄

ZnSO₄

22 / 59

Which of the following is an example of a redox reaction?

Mg + 2HCl → MgCl₂ + H₂

CaCO₃ → CaO + CO₂

NaOH + HCl → NaCl + H₂O

2NaCl → 2Na + Cl₂

23 / 59

Reaction of sodium thiosulphate with iodine gives

(d) sulphite ion

(b) sulphide ion

(a) tetrathionate ion

24 / 59

Which of the following reactions is a redox reaction?

NH₃ + HCl → NH₄Cl

2Fe + 3H₂SO₄ → Fe₂(SO₄)₃ + 3H₂

NaCl + H₂O → NaOH + HCl

CaCO₃ → CaO + CO₂

25 / 59

What is the oxidation state of oxygen in H₂O₂?

-1

-2

26 / 59

Which of the following statements about oxidation numbers is true?

All of the above are true.

Oxidation numbers are assigned to individual atoms.

The sum of the oxidation numbers in a compound must be zero.

Oxidation numbers can be negative, positive, or zero.

27 / 59

The oxidation number of V in Cs₄Na(HV₁₀O₂₈) is

(a) +2

(b) +5

(d) +3

28 / 59

What is the reducing agent in the following reaction: 2AgNO₃ + Cu → Cu(NO₃)₂ + 2Ag?

AgNO₃

Cu(NO₃)₂

29 / 59

What is the oxidizing agent in the following reaction: Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag?

AgNO3AgNO₃

Cu(NO₃)₂

30 / 59

Which of the following is an example of a redox reaction where the oxidation number of nitrogen changes?

b) 2NH₃ + 3O₂ --------> 2NO + 3H₂O

d) 2HNO₃ + Mg --------> Mg(NO₃)₂ + 2H₂O

a) N₂ + 3H₂ --------> 2NH₃

c) 2NaNO₃ --------> 2NaNO₂ + O₂

31 / 59

The oxide, which cannot act as a reducing agent is

(a) CO₂

(d) SO₂

(b) ClO₂

32 / 59

The oxidation number of phosphorous in ATP (adenosine triphosphate) is

(a) 2

(b) 3

(d) 5

33 / 59

Without losing its concentration, ZnCl₂ solution cannot be kept in contact with

(d) Ag

(a) Pb

(b) Al

34 / 59

In a redox reaction, the reducing agent

a) Gains electrons

b) Loses electrons

d) Is neither oxidized nor reduced

c) Does not change its oxidation state

35 / 59

Zn gives H₂ gas with H₂SO₄ and HCl but not with HNO₃ because

(b) HNO₃ is weaker acid then H₂SO₄ and HCl

(d) NO^3– is reduced in preference to hydronium ion

(a) Zn acts as oxidizing agent when reacts with HNO₃

36 / 59

Which of the following is a redox reaction?

(b) CaC₂O₄ + 2HCl ---------------- > CaCl₂ + H₂C₂O₄

(a) NaCl + KNO₃ ---------------- > NaNO₃ + KCl

(d) Zn + 2AgCN ---------------- > 2Ag + Zn(CN)₂

37 / 59

Which of the following is an example of a redox reaction?

d) HCl + NaOH ----------> NaCl + H₂O

c) NH₃ + HCl ----------> NH₄Cl

b) CH₄ + 2O₂ ----------> CO₂ + 2H2O

a) NaCl + H₂O ----------> NaOH + HCl

38 / 59

What is the oxidizing agent in the following reaction: Cl₂ + 2KBr → 2KCl + Br₂?

Cl₂

Br₂

KBr

KCl

39 / 59

Which of the following is the oxidizing agent in the reaction:

2H₂S + SO₂ ------> 3S + 2H₂O?

d) H₂O

b) SO₂

a) H₂S

c) S

40 / 59

The oxidation state of oxygen in O₂PtF₆ is

(a) zero

(d) +l

(b) – ½

41 / 59

Which of the following statements is true about redox reactions?

a) They involve the transfer of protons only.

c) They always result in the formation of a gas.

d) They can only occur in acidic solutions.

b) They always involve the transfer of electrons.

42 / 59

Oxidation numbers of P in PO₄^3–, of S in SO₄^2– and that of Cr in Cr₂O₇ ^2– are respectively

(b) +5, +3 and +6

(a) +3, +6 and +5

(d) +5, +6 and +6

43 / 59

Which of the following is an example of a disproportionation reaction?

c) 2HCl + Mg ---------- > MgCl₂ + H₂

a) 2Na + Cl₂ ---------- > 2NaCl

d) Cu + 2AgNO₃ ---------- > Cu(NO₃)₂ + 2Ag

b) 2H₂O₂ ---------- > 2H₂O + O₂

44 / 59

Which of the following statements is true?

Reduction is the gain of electrons.

None of the above is correct.

Both A and B are correct.

Oxidation is the loss of electrons.

45 / 59

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

(a) HNO₃, NO, N₂, NH₄Cl

(b) HNO₃, NO, NH₄Cl, N2

(d) NH₄Cl, N₂, NO, HNO₃

46 / 59

The oxidation state of Cr in CrO₅ is

(a) –6

(b) +12

(d) +4

47 / 59

In the silver plating of copper, K[Ag(CN)₂] is used instead of AgNO₃. The reason is

(b) more voltage is required

(d) less availability of Ag⁺ ions, as Cu cannot displace Ag from [Ag(CN)_2^–] ion

(a) a thin layer of Ag is formed on Cu

48 / 59

Hot concentrated sulphuric acid is a moderately strong oxidizing agent. Which of the following reactions does not show oxidizing behaviour?

(d) CaF₂ + H₂SO₄ → CaSO₄ + 2HF

(b) S + 2H₂SO₄ → 3SO₂ + 2H₂O

(a) Cu + 2H₂SO₄ → CuSO₄ + SO₂ + 2H₂O

49 / 59

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

(a) 7.5 moles

(d) 0.4 moles

(b) 0.2 moles

50 / 59

The pair of compounds that can exist together is

(d) FeCl₃, KI

(b) HgCl₂, SnCl₂

(a) FeCl₃, SnCl₂

51 / 59

When white phosphorus reacts with caustic soda, the products are PH₃ and NaH₂PO₂ .This reaction is an example of

(b) reduction

(a) oxidation

(d) neutralization

52 / 59

Removal to basic oxide from metal before electroplating is known as

(d) Anodizing

(b) Galvanizing

(a) Poling

53 / 59

What is the oxidation state of carbon in methane, CH₄?

-4

-2

54 / 59

Which of the following is an example of a disproportionation reaction?

2K + Cl₂ → 2KCl

2HCl + Mg → MgCl₂ + H₂

2H₂O₂ → 2H₂O + O₂

2Na + 2H₂O → 2NaOH + H₂

55 / 59

Which of the following is not a redox reaction?

(a) MgCO₃ ---------> MgO + CO₂

(d) SnCl₄ ---------> SnCl2 + Cl₂

(b) O₂ + 2H₂ ---------> 2H₂O

56 / 59

Oxidation state of Fe in Fe₃O₄ is

(a) 5/4

(b)4/5

(d)8/3

57 / 59

Among the following molecules, in which does bromine show the highest oxidation number?

(a) Hg₂(BrO₃)₂

(d) Br₂

(b) Br–Cl

58 / 59

Which of the following elements has a variable oxidation state?

Oxygen

Chromium

Carbon

Nitrogen

59 / 59

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

(b) 0 to + 4

(a) + 4 to + 4

(d) 0 to – 4

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Redox Reactions NEET Questions

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