Tag: electroplating and its application

Questions Related to electroplating and its application

An oxide of iron from the following is:

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

  1. mud

  2. dust

  3. rust

  4. none of these

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Correct Option: C
Explanation:

Oxide of iron is rust. Iron in presence of oxygen forms iron oxide. The chemical name of rust is ferrous oxide. It further oxidises to ferric oxide.

Iron can be prevented from rusting by:

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

  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.

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Correct Option: A,C
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

Which of the following statements is/are incorrect ?

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

  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.

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Correct Option: A,C,D
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

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

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

  1. Basic copper carbonate

  2. Copper sulphide

  3. Basic copper sulphate

  4. Copper oxide

Show answer
Correct Option: A,C
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

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

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

  1. increases

  2. decreases

  3. sharply decreases

  4. does not effect

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Correct Option: A
Explanation:

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

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

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

  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

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Correct Option: B
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.

Corrosion of metals can be prevented when contact between metal and ________ is cut off.

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

  1. nitrogen

  2. hydrogen

  3. oxygen

  4. carbon

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Correct Option: C
Explanation:

Corrosion is basically oxidation of metal in presence of oxygen. So it can be prevented by cutting off ${ O } _{ 2 }$

Rusting of iron involves:

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

  1. oxidation

  2. reduction

  3. decomposition

  4. displacement

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Correct Option: A
Explanation:

Rusting of iron involves oxidation.

Which of the following statement is not true?

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

  1. metals produce a ringing sound when struck hard

  2. copper doesn't get rusted

  3. coal and sulphur are soft and dull in appearance

  4. magnesium and phosphorous burn vigorously in air

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Correct Option: B
Explanation:

Copper gets oxidized to form green oxide layer in the presence of air but this is not rusting, this layer is known as patina means tarnishing of copper into bluish green layer.

Lead pipes are readily corroded by:

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

  1. water

  2. acetic acid

  3. conc. $H _2SO _4$

  4. dil. $H _2SO _4$

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Correct Option: B
Explanation:

Corrosion of lead is strongly accelerated by traces of acetic acid. Acetic acid in the presence of oxygen rapidly attacks lead and produces very soluble lead(II) acetate which precludes the use of lead to process or store wine or fruit juice.