Tag: changes around us

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Questions Related to changes around us

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.

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

When a corroded metal object is rubbed by a sand paper then:

  1. outer metal surface is removed

  2. metal becomes thin

  3. outer corroded layer will be removed

  4. all of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The metals lose their shine and become dull when exposed to air for a long time. Due to the formation of oxides, when the surface is rubbed by a sand paper, then the outer corroded layer is removed.

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

If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of:

  1. $CuCO _3$
  2. $CuSO _4$
  3. $CuCO _3.Cu(OH) _2$
  4. $CuO$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Copper reacts with $CO _2$ present in the air and forms a green coating on its surface due to the formation of basic copper carbonate.


$2Cu+O _2+CO _2+H _2O\rightarrow CuCO _3.Cu(OH) _2$

So, the correct option is $C$

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

According to the electrochemical concept, corrosion occurs at :

  1. anodic area of metal

  2. cathodic area of metal

  3. both cathodic and anodic areas of metal

  4. neither cathodic area nor anodic areas of metal
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Corrosion can be defined as the deterioration of materials by chemical processes. 

Of these, the most important by far is electrochemical corrosion of metals in which the oxidation process $M \rightarrow M^+ + e^-$ is facilitated by the presence of a suitable electron acceptor. This is possible because metals are conductive and so, the electrons can flow through the metal from the anodic to the cathodic regions. 
Metallic corrosion occurs when metal atoms are oxidized and subsequently leave the metal lattice as ions. The oxidation reaction of the metal is referred to as the anodic half-reaction. The areas on a metal surface where oxidation occurs are referred to as anodes.

Option A is correct.

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

Mark the correct statement:
a) Damp air alone supplies both things needed for corrosion.
b) Ordinary water supplies both air and water for corrosion.
c) Moist air can't provide both things.

  1. a, b

  2. a, c

  3. b, c

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Damp air supplies both the things needed for rusting of Iron. Ordinary water has some air dissolved in it. So, it can do the same.

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

What is corrosion?

  1. When metal is gradually destroyed through chemical reactions

  2. When metal is created through chemical reactions

  3. When a redox reaction takes place

  4. When a metal is destroyed after exposure to a gas

  5. When a solid is destroyed through chemical reactions
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Corrosion occurs when a redox reaction takes place.

Corrosion is a natural process, which converts a refined metal to a more chemically-stable form, such as its oxide, hydroxide, or sulfide. It is the gradual destruction of materials by chemical and/or electrochemical reaction with their environment.
It also gradually destroys the element through chemical reactions

Hence, the correct options are $A$ and $C$

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

If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of:

  1. $CuSO _{4}$
  2. $CuCO _{3}$
  3. $Cu(NO _{3}) _{2}$
  4. $CuO$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The green coat is due to the basic copper carbonate formation and is a mixture of copper carbonate and copper hydroxide $(CuCO _3$ and $Cu(OH) _2)$.

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

Which of the following metals has been used for building boats because it has resistance to corrosion by sea water?

  1. Copper

  2. Nickel

  3. Fungsten

  4. Titanium
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Titanium is used for building boats.

Inert metals which do not react with gases in air seen as oxygen are found to be non-corrosive.
It is corrosion resistance because it forms stable, protective, oxide film when $Ti$ is exposed to oxide film.