Tag: changes - physical and chemical

Questions Related to changes - physical and chemical

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

Show answer
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.

The tarnishing of silver ornaments in atmosphere is due to:

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

  1. $Ag _{2}O$

  2. $Ag _{2}S$

  3. $Ag _{2}CO _{3}$

  4. $Ag _{2}SO _{4}$

Show answer
Correct Option: A,B
Explanation:

The tarnishing of silver ornaments in atmosphere is due to formation of silver oxide $Ag _{2}O$ and silver sulphide $Ag _{2}S$.

$2Ag\, +\, \displaystyle 
\frac{1}{2}{O _{2}}\, \rightarrow\, Ag _{2}O$

$2Ag\, +\, H _{2}S\, \rightarrow\, Ag _{2}S\, +\, H _{2}$

Hence, option A and B are correct.

Which metal is protected by a layer of its own oxide?

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

  1. $Al$

  2. $Ag$

  3. $Au$

  4. $Fe$

Show answer
Correct Option: A
Explanation:

Aluminium in air is ordinarily protected by a molecule-thin layer of its own oxide. This aluminium oxide layer serves as a protective barrier to the underlying aluminium itself and preventing chemical reactions with the metal.

Rusting of iron is catalysed by which of the following:

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

  1. $Fe$

  2. $Zn$

  3. O$ _{2}$

  4. $H^{+}$

Show answer
Correct Option: D
Explanation:

The rusting or iron occurs in acidic medium. Hence it is catalyzed by $ { H }^{ + } $ ions.

Hence, correct option is D.