Redox Reactions Test

Result

Redox Reactions Test - 4

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

The standard redox potentials (E^o) of the following reactions are as follows.

I. MnO₄^- + 8H⁺ + 5e^- Mn²⁺ + 4H₂O E^o = 1.51 V
II. Sn²⁺ Sn⁴⁺ + 2e^- E^o = -0.15 V
III. Cr₂O₇^2- + 14H⁺ + 6e^- 2Cr³⁺ + 7H₂O E^o = 1.33 V
IV. Ce³⁺ Ce⁴⁺ + e^- E^o = -1.61 V

In which of the following options is the oxidising power of the various ions wrongly related?

A
Cr₂O₇^2- > MnO^-₄

B
Ce⁴⁺ > Sn⁴⁺

C
Ce⁴⁺ > MnO^-₄

D
MnO^-₄ > Sn⁴⁺
Question 2
1 / -0

Directions: The following question has four choices out of which ONLY ONE is correct.

In acidic medium, dichromate ion oxidizes ferrous ion to ferric ion. If the gram molecular weight of potassium dichromate is 294 g, its gram equivalent weight is

A
294 g

B
147 g

C
49 g

D
24.5 g
Question 3
1 / -0

Directions: The following question has four choices out of which ONLY ONE is correct.

If equal volumes of 1 M KMnO₄ and 1 M K₂Cr₂O₇ solutions are allowed to oxidize Fe (II) to Fe (III) in acidic medium, then Fe (II) oxidization will be

A
more by KMnO₄

B
more by K₂Cr₂O₇

C
equal in both cases

D
Cannot be determined
Question 4
1 / -0

Directions: The following question has four choices out of which ONLY ONE is correct.

Consider the following half reactions:

Zn²⁺ Zn(s); E⁰ = - 0.76V
Cu²⁺ Cu(s); E⁰ = - 0.34V

Which of the following reactions is spontaneous?

A
Zn²⁺ + Cu Zn + Cu²⁺

B
Cu²⁺ + Zn Cu + Zn²⁺

C
Zn²⁺ + Cu²⁺ Zn + Cu

D
None of these
Question 5
1 / -0

In the balanced equation H₂SO₄ + x HI H₂S + y I₂ + z H₂O, what are the values of x, y and z?

A
x = 3, y = 5, z = 2

B
x = 4, y = 8, z = 5

C
x = 8, y = 4, z = 4

D
x = 5, y = 3, z = 4
Question 6
1 / -0

Redox reaction between copper and aqueous solution of silver nitrate happens when copper rod is dipped in silver nitrate solution. What happens in the final stage?

A
the solution turns intense blue; and silver is deposited on copper rod

B
silver deposits on the rod; Ag+(aq) is oxidised to Ag(s)

C
copper deposits in the solution; Cu(aq) is reduced to Cu₂⁺ (s)

D
silver deposits in the solution; Ag+(aq) is reduced to Ag(s).

Solution

This is due to the formation of Cu²⁺ ions in the solution illustrated in following ionic reaction:

Cu(S)+2Ag⁺(aq)--------------˃Cu²⁺(aq)+2Ag(s)

Here, Cu is oxidized to Cu²⁺ (means relasing of 2 electrons from Cu to Cu²⁺ ) and Ag⁺ is reduced to Ag(s) (means gaining of 2 electrons from 2Ag⁺ to 2Ag ) and thus, silver converted into solid state and deposited on copper rod.
Question 7
1 / -0

The mass of H₂O₂ that is completely oxidised with 31.2 g of KMnO₄ (molar mass = 158 g mol^–1) in acidic medium is

A
12 g

B
15 g

C
17 g

D
1 g
Question 8
1 / -0

The formation of sodium chloride involves two half reaction, which clearly show involvement of electrons.
2 Na (s) → 2 Na + (g) + 2e Cl2 (g) + 2e → 2 Cl (g)
Sum of the half reactions gives
2 Na(s) +Cl2 (g) → 2 Na+ Cl (s) or 2 NaCl (s)

In terms of electron-transfer change, name the oxidising agent(s) and reducing agent(s)

A
Oxidising agent: Chlorine and Reducing agent: Sodium

B
reducing agents:Chlorine, oxygen and oxidising agents:sodium and sulphur

C
oxidising agents:Chlorine, oxygen and reducing agents:sodium and sulphur

D
reducing agents:Chlorine, oxygen and sulphur and oxidising agent:sodium
Solution
According to the modern concept, loss of electrons is oxidation whereas gain of electrons is reduction.Redox reaction involves two half reactions, one involving loss of electron or electrons (oxidation) and the other involving gain of electrons or electrons (reduction)
- Oxidizing agent is a species which can gain one or more electrons.
- Reducing agent is a species which can lose one or more electrons.
In the given reaction Sodium(Na) is loosing 2 electrons, thus it is the reducing agent. Chlorine(Cl) is gaining 2 electrons , thus it is oxidising agent.
Question 9
1 / -0

HBr and HI can reduce sulphuric acid. HCl can reduce KMnO₄ and HF can reduce

A
H₂SO₄

B
KMnO₄

C
K₂Cr₂O₇

D
None of these
Question 10
1 / -0

What is the reduction product in the reaction 2KMnO₄ + 16HCl 5Cl₂ + 2MnCl₂ + 2KCl + 8H₂O?

A
Cl₂

B
MnCl₂

C
H₂O

D
KCl
Question 11
1 / -0

The reaction is

A
intramolecular redox change

B
intermolecular redox change

C
disproportionation reaction

D
None of these
Question 12
1 / -0

Directions: The following question has four choices out of which ONLY ONE is correct.

The oxidation number of carbon in CH₂O is

A
- 2

B
+ 2

C
0

D
+ 4
Question 13
1 / -0

For the reaction between KMnO₄ and H₂O₂, the number of electrons transferred per mole of H₂O₂ is:

A
1

B
3

C
2

D
4
Question 14
1 / -0

Oxidation and reduction always occur simultaneously, hence, the word “redox” was coined for this class of chemical reactions. In the following redox reaction, identify the species undergoing oxidation and reduction:

3Fe₃O₄(s) + 8 Al (s) → 9 Fe (s) + 4Al₂O₃(s)

A
Fe₃O₄is oxidised, Fe is reduced

B
Al₂O₃ is reduced, Fe₃O₄ is oxidised

C
Aluminium (Al) is oxidised, (Fe₃O₄) is reduced

D
Fe₃O₄ is oxidised, Aluminium is reduced

Solution

In the above reaction oxygen is transferred from Fe₃O₄ to Al, so Fe₃O₄ is reduced while Al is oxidised.

As per definition of oxidation and reduction , loss of oxygen i.e reduction occurs in Fe₃O₄ and gain of oxygen i.e Oxidation occurs in Al.
Question 15
1 / -0

The oxidation state of an element in a particular compound can be defined as:

A
The charge acquired by its atom on the basis of electronegative consideration from other atoms in the molecule.

B
The residual charge acquired by its atom after removing all electronegative atoms from the molecule.

C
The valency of the most electronegative atom present in the molecule.

D
The total number of electrons accepted by an atom to form a molecule.

Solution

The oxidation state of an element in a particular compound can be defined as the charge acquired by its atom on the basis of electronegative consideration from other atoms in the molecule.
In other words, it represents the number of electrons gained or lost by the element or ion in the reaction that formed the compound. It is expressed as a positive or negative number that represents the ionic charge. For example, in sodium chloride, the oxidation states of sodium and chlorine are +1 and -1 respectively.
Hence, the correct option is (A).
Question 16
1 / -0

The reduction potentials of A, B, C and D are 0.8 V, 0.79 V, 0.34 V and -2.37 V, respectively. Which element displaces all the other three elements?

A
B

B
A

C
D

D
C
Question 17
1 / -0

Oxygen has a positive oxidation state in

A
O₂

B
RbO₃

C
H₂O₂

D
O₂F₂
Question 18
1 / -0

In which of the following compounds does the carbon atom have zero oxidation state?

A
CH₄

B
CHCl₃

C
CH₂Cl₂

D
CCl₄
Question 19
1 / -0

Directions: The following question has four choices out of which ONLY ONE is correct.

One mole of acidified K₂Cr₂O₇ on reaction with excess KI will liberate ___ mole(s) of I₂.

A
6

B
1

C
7

D
3
Question 20
1 / -0

The electron releasing tendency of the metals, zinc, copper and silver is in the order:

A
Ag>Cu>Zn

B
Cu>Ag>Zn

C
Zn>Cu>Ag

D
Zn>Ag>Cu

Solution

Zinc relases electrons to copper and copper releases electron to silver therefore the electron releasing tendency of the metals, zinc, copper and silver is in the order Zn>Cu>Ag.This is on the basis of electrochemical series or metal activity series.