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Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Assertion: Rusting of Fe is quicker in saline water than in ordinary water.
Reason: Presence of $Na^+$ and $Cl^-$ ions increase the conductance of the saline water.

  1. Both Assertion and Reason are true and Reason is the correct explanation of Assertion

  2. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion

  3. Assertion is true but Reason is false

  4. Assertion is false but Reason is true

  5. Both Assertion and Reason are false
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The $Na^{\oplus}$ and $Cl^{\ominus}$ present in saline water increase the conductance of the solution in contact with the metal surface. This accelerates the formation of $Fe^{2+}$ ions and hence that of rust, $Fe _2O _3 \cdot xH _2O$

Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

No rusting takes place in absence of moisture. 

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Rust is an iron oxide, usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Given sufficient time, oxygen and water, any iron mass will eventually convert entirely to rust and disintegrate. No rusting takes place in absence of moisture. 

Multiple choice chemistry changes - physical and chemical effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Iron can be prevented from rusting by:

  1. connecting iron to more electropositive metal a case of cathodic protection.

  2. connecting iron to more electropositive metal a case of anodic protection.

  3. connecting iron to less electropositive metal a case of anodic protection.

  4. connecting iron to less electropositive metal a case of cathodic protection.
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

Cathodic protection: A technique to control corrosion of a metal surface by making it work as a cathode of an electrochemical cell by placing in contact with the metal to be protected another more easily corroded metal to act as the anode of the electrochemical cell. Most commonly used to protect steel, water pipelines, and storage tanks.

Anodic protection: A technique to control corrosion of a metal by making it work as anode developing a passive film on the metal. It used in extremely corrosive conditions and most extensively used to store and handle sulphuric acid container.

Hence, option A and C are correct

Multiple choice chemistry changes - physical and chemical effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Which of the following statements is/are incorrect ?

  1. Rust is $Fe _{2}O _{3}$

  2. Zn - Cu cell is called Daniell cell.

  3. Saline water slows down rusting.

  4. Pure metals undergo corrosion faster than impure metals.
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

Correct statements are given below:

a. Rust is $Fe _{2}O _{3}.xH _{2}O$.
b. Correct.
c. Saline water fastens the rusting.
d. Pure metals undergo corrosion slower than impure metals.

Hence, options A, C and D are correct options

Multiple choice chemistry changes - physical and chemical effects of oxidation reactions in daily life corrosion of metals electroplating and its application

In the atmosphere of industrial smog, copper corrodes to form:

  1. Basic copper carbonate

  2. Copper sulphide

  3. Basic copper sulphate

  4. Copper oxide
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation
Reactions taking place are:
$8Cu\, +\, 6H _{2}O\, +\, 2SO _{2}\, +\, 5O _{2}\, \rightarrow\,  2[CuSO _{4}.3Cu(OH) _{2}]$ 

$2Cu\, +\, H _{2}O\, +\, CO _{2}\, +\, O _{2}\, \rightarrow\,  [CuCO _{3}.Cu(OH) _{2}]$

Hence, options A and C are correct
Multiple choice chemistry changes - physical and chemical effects of oxidation reactions in daily life corrosion of metals electroplating and its application

The presence of electrolytes ................ the rate of corrosion. 

  1. increases

  2. decreases

  3. sharply decreases

  4. does not effect
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The presence of electrolyte increase the concentration of electron and thus increasing the mobility of electron due to which rate of corrosion increases.

Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Aluminium is more reactive than iron. But aluminium is less easily corroded than iron because:

  1. aluminium is a noble metal

  2. oxygen forms a protective oxide layer on aluminium surface

  3. iron unergoes reaction easily with water

  4. iron forms both mono and divalent ions
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Corrosion resistance of aluminium is due to formation of thin layer of aluminium oxide that forms when metal is exposed to air and prevents further oxidation. It is called as protective passivation.