Tag: changes - physical and chemical

Quizzes (3) Questions (15)

Questions Related to changes - physical and chemical

Multiple choice chemistry changes - physical and chemical physical changes changes and their classification physical changes

Maximum conductivity would be of : 

  1. $K _{3}Fe(CN) _{6}[0.1 M Solution]$
  2. $K _{3}Ni(CN) _{6}[0.1 M Solution]$
  3. $FeSO _{4}.Al _{2}(SO _{4}) _{3}.24H _{2}O[0.1 M Solution]$
  4. $Na _{3}[Ag(S _{2}O _{3}) _{2}][0.1 M Solution]$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Conductivity depends on the number of ions produced in solution. FeSO4.Al2(SO4)3.24H2O (Alum) dissociates into the most ions per formula unit compared to the complex salts listed, leading to higher molar conductivity.

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

When the lead accumulator is charged, it acts as:

  1. an electrolytic cell

  2. a galvanic cell

  3. a Daniel cell

  4. none of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

During the charging of a lead accumulator cell, the electical energy is stored in the form of chemical energy. Thus, the electrical energy derives non-spontaneous chemical reactions. Hence, during charging, the lead accumulator cell acts as an electrolytic cell.

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

When lead storage battery is charged:

  1. lead dioxide dissolves

  2. sulphuric acid is regenerated

  3. lead electrode becomes coated with lead sulphate

  4. the concentration of sulphuric acid decreases
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

During charging of lead storage battery, sulphuric acid is regenerated. The net cell reaction during charging is $ PbS{ O } _{ 4 } +{ 2{ H } _{ 2 }O  }  \xrightarrow {  }  Pb  +  Pb{ O } _{ 2 }  +  2{ H } _{ 2 }{ SO } _{ 4 }  $

Hence, option B is correct.

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

Number of Faradays involved in the net reaction of Lead accumulator is __________.

  1. 1

  2. 0.5

  3. 2

  4. cannot be predicted
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

For lead accumulator battery, the oxidation reaction at anode  requires two moles of electrons. Similarly, the reduction reaction at cathode  requires two moles of electrons. Hence, the number of Faradays involved in the net reaction of Lead accumulator is 2.
Note: 1 Faraday is equal to the amount of charge on 1 mole of electrons.

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

During the charging of lead accumulator battery voltage varies from:

  1. $2.15$ V to $1.88$ V
  2. $1.88$ V to $2.0$ V
  3. $1.88$ V to $2.15$ V

  4. does not change
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When the lead accumulator battery is charged, the voltage range is 1.88 V to 2.15 V as the concentration of sulphuric acid varies from 5% to 40%.


Hence, option C is correct.

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

In electrochemical passivity:

  1. thin visible oxide film is formed

  2. thin invisible oxide film is formed

  3. thick visible oxide film is formed

  4. thick invisible oxide films formed
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

During electrochemical passivisation, the metal surface is made inactive by formation of thin invisible oxide layer on the surface. 


This is done by the oxidation of metal on metal surface.

Hence, option B is correct.

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

Iron is not protected from rusting by:

  1. galvanization
  2. electroplating with $Ni$ or $Cr$

  3. heating the iron to redness in steam
  4. treating it with $H _{3}PO _{4}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Phosphoric acid will not form a protective coating of iron oxide on the surface of iron. A strong oxidizing agent such as nitric acid is required for this process.

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

The technique of protecting a metal from corrosion by connecting it to a second metal (that is more easily oxidized) is called:

  1. galvanization

  2. anodic protection

  3. cathodic protection

  4. sacrificial protection
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In cathodic protection, the more easily oxidized metal is attached to the metal which is to be protected. This results in corrosion of more easily oxidized metal. The other metal is thus protected from corrosion.

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