Tag: changes - physical and chemical

Quizzes (3) Questions (15)

Questions Related to changes - physical and chemical

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

The tarnishing of silver ornaments in atmosphere is due to:

  1. $Ag _{2}O$
  2. $Ag _{2}S$
  3. $Ag _{2}CO _{3}$
  4. $Ag _{2}SO _{4}$
Reveal answer Fill a bubble to check yourself
A,B Correct answer
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.

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

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

  1. $Al$
  2. $Ag$
  3. $Au$
  4. $Fe$
Reveal answer Fill a bubble to check yourself
A Correct answer
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.