Chemistry Test 175

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Chemistry Test 175

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Weekly Quiz Competition

Question 1
4 / -1

Which of the following processes does not involve either oxidation or reduction?

A
Formation of slaked lime from quick lime

B
Heating Mercuric Oxide

C
Formation of Manganese Chloride from Manganese oxide

D
Formation of Zinc from Zinc blende

Solution

CaO + H₂O → Ca(OH)₂

Oxidation number doesn’t change so its not a redox reaction.
Question 2
4 / -1

A standard reduction electrode potentials of four metals are A = -0.250 V, B = -0.140 V, C = -0.126 V, D = -0.402 V The metal that displaces A from its aqueous solution is:

A
A

B
B

C
C

D
D

Solution

Reduction potential of D is minimum i.e. −0.402 V. Thus oxidation potential of D is maximum i.e. to +0.402 V. D can oxidise itself and reduce other. The aqueous solution A will be present in its ionic form and can be reduced by D as its reduction potential is higher than D.
Question 3
4 / -1

Oxygen has an oxidation state of +2 in the compound

A
F₂O

B
None of these

C
CO₂

D
H₂O

Solution

In F₂O

⇒ 2 × (−1) + x = 0

⇒ x = +2
Question 4
4 / -1

The reduction potential values of M, N and O are +2.46 V, -1.13 V, -3.13 V respectively. Which of the following orders is correct regarding their reducing property?

A
O > N > M

B
M > O > N

C
M > N > O

D
O > M > N

Solution

Given Reduction Potential: M → +2.46V N → +1.13V O → −3.13V We know that the electrode which has more reduction potential is a good oxidizing agent and has least reducing power. While the electrode which has less reduction potential, it has more reducing power. Therefore, Order of reducing power is: – O > M > N
Question 5
4 / -1

Alkaline medium inhibits the rusting of iron, because

A
OH^- are produced

B
Non availability of H⁺ ions which reduces oxidation of Fe to Fe⁺² ions

C
OH^- ions are not produced

D
Rate of oxidation of iron is high

Solution

The reaction 4Fe + 3O2 + 6H2O → 4Fe(OH)3 takes place in the acidic medium as we see and Fe is converted to Fe⁺².

Alkalis are compounds that have OH^- ions in them, i.e, they liberate hydroxide ions on dissociation.

The alkalis are generally bases and they react with acids to neutralize the solution to produce water.

The hydroxyl ions are basically consuming the protons or H⁺to form water.

Thus, the reaction medium doesn't have any hydronium ion left and the oxidation reaction of iron cannot proceed.

Hence, we can say that an alkaline medium inhibits the rusting of iron, because of the non-availability of H+ ions which reduces oxidation of Fe to Fe+2 ions.
Question 6
4 / -1

The number of moles of KMnO₄ reduced by one mole of KI in alkaline medium is

A
One

B
Two

C
Five

D
One fifth.

Solution

In alkaline medium the reduction of KMnO4 with KI will takes place as

2 KMnO₄ + H₂O → 2 KOH + 2 MnO₂ KI + 3[O] → KIO₃

Hence the overall reaction is KI + 2KMnO₄ + H₂O → KIO₃+ 2 KOH + 2 MnO₂

So, one mole of KI will reduced two moles of KMnO₄
Question 7
4 / -1

What is known as Autooxidation?

A
Formation of H₂O by the oxidation of H₂O₂.

B
Formation of H₂O₂ by the oxidation of H₂O.

C
Both (1) and (2) are true

D
None of the above

Solution

Autoxidation is any oxidation that occurs in presence of oxygen. The term is usually used to describe the degradation of organic compounds in air (as a source of oxygen). Autoxidation produces hydroperoxides and cyclic organic peroxides. These species can react further to form many products. The process is relevant to many phenomena including aging, paint, and spoilage of foods, degradation of petrochemicals, and the industrial production of chemicals. Autoxidation is important because it is a useful reaction for converting compounds to oxygenated derivatives, and also because it occurs in situations where it is not desired (as in the destructive cracking of the rubber in automobile tires or in rancidification). Water automatically gets oxidised to hydrogen peroxide.
Question 8
4 / -1

Which of the following statements regarding sulphur is incorrect ?

A
S₂ molecule is paramagnetic.

B
The vapour at 200° C consists mostly of S₈ rings.

C
At 600°C the gas mainly consists of S₂ molecules.

D
The oxidation state of sulphur is never less than +4 in its compounds.

Solution

Oxidation state of oxygen family Oxygen shows -2, +2 and -1

Oxidation states other elements show +2, +4 and +6 oxidation states

In H₂S, the oxidation state of S is -2. Oxidation state of S lie between -2 to +6.

Option (A)

S2 molecule is paramagnetic.

This option is incorrect.

Option (B)

The vapour at 200° C consists mostly of S8 rings.

This option is incorrect.

Option (C)

At 600° C the gas mainly consists of S₂ molecules.

This option is incorrect.

Option (D)

The oxidation state of sulphur is never less than +4 in its compounds.

This option is correct.
Question 9
4 / -1

The number of types of bonds between two carbon atoms in calcium carbide is

A
Two sigma, two pi

B
One sigma, two pi

C
One sigma, one pi

D
Two sigma, one pi

Solution

A single bond between two atoms is always considered as sigma bond.

A double bond between two atoms is always considered as one sigma and one pi bond

A triple bond between two atoms is always considered as one sigma bond and two pi bonds.

So according to the given structure CaC₂ (Calcium carbide) has 1 sigma and 2 pi bonds
Question 10
4 / -1

The oxidation process involves

A
Increase in oxidation number

B
Decrease in oxidation number

C
No change in oxidation number

D
none of the above

Solution

Oxidation process Involves:-

(i) Addition of O₂ or electronegative element
(ii) Removal of H/ electropositive element
(iii) Loss of electrons
(iv) Increase in oxidation number

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Chemistry Test 175

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Chemistry Test 175

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SHARING IS CARING

Question 1

Formation of slaked lime from quick lime

Heating Mercuric Oxide

Formation of Manganese Chloride from Manganese oxide

Formation of Zinc from Zinc blende

Solution

Question 2

A

B

C

D

Solution

Question 3

F2O

None of these

CO2

H2O

Solution

Question 4

O > N > M

M > O > N

M > N > O

O > M > N

Solution

Question 5

OH- are produced

Non availability of H+ ions which reduces oxidation of Fe to Fe+2 ions

OH- ions are not produced

Rate of oxidation of iron is high

Solution

Question 6

One

Two

Five

One fifth.

Solution

Question 7

Formation of H2O by the oxidation of H2O2.

Formation of H2O2 by the oxidation of H2O.

Both (1) and (2) are true

None of the above

Solution

Question 8

S2 molecule is paramagnetic.

The vapour at 200° C consists mostly of S8 rings.

At 600°C the gas mainly consists of S2 molecules.

The oxidation state of sulphur is never less than +4 in its compounds.

Solution

Question 9

Two sigma, two pi

One sigma, two pi

One sigma, one pi

Two sigma, one pi

Solution

Question 10

Increase in oxidation number

Decrease in oxidation number

No change in oxidation number

none of the above

Solution

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F₂O

CO₂

H₂O

OH^- are produced

Non availability of H⁺ ions which reduces oxidation of Fe to Fe⁺² ions

OH^- ions are not produced

Formation of H₂O by the oxidation of H₂O₂.

Formation of H₂O₂ by the oxidation of H₂O.

S₂ molecule is paramagnetic.

The vapour at 200° C consists mostly of S₈ rings.

At 600°C the gas mainly consists of S₂ molecules.