Tag: electroplating and its application

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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.

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

Which of the following statement is not true?

  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
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Lead pipes are readily corroded by:

  1. water

  2. acetic acid
  3. conc. $H _2SO _4$
  4. dil. $H _2SO _4$
Reveal answer Fill a bubble to check yourself
B Correct answer
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.