Electrode System, Corrosion and Analytical Techniques

The electrode potential of saturated calomel electrode is

• 0.2422V

• 0.281V

• 0.181V

• 0.333V

Calomel is ____

• A paste of Hg

• A paste of Hg & HgCl₂

• A paste of Hg & HgCl

• A paste of Hg & Hg₂Cl₂

Corrosion is ____

• Oxidation

• Reduction

• Electrolysis

• All the above

The corrosion caused by the direct chemical action of environmental gases or anhydrous liquids on the metal surfaces is called

• Pitting corrosion

• Wet corrosion

• dry corrosion

• Electrochemical corrosion

In electrochemical corrosion

• Anode undergoes oxidation

• Anode undergoes reduction

• Cathode undergoes oxidation

• Both undergo oxidation

The localized attack of a corroding environment leading to the formation of holes in an otherwise relatively unattacked surface of a metal is called

• Water-line corrosion

• Galvanic corrosion

• Concentration cell corrosion

• Pitting corrosion

Which of the following is an example of wet corrosion

• Corrosion of Iron in presence of anhydrous CaCl₂

• Corrosion of Titanium in dry Chlorine

• Corrosion of metal in 0.1M NaCl solution

• Corrosion due to furnace gases

Rate of corrosion is highest when

• Iron (E^o= -0.44V) is in contact with zinc (E^o=-0.76V)

• Iron (E^o= -0.44V) is in contact with copper (E^o=0.34V)

• zinc(E^o= -0.76V) is in contact with tin (E^o=-0.14V)

• Gold (E^o= 1.38V) is in contact with silver (E^o=0.8V)

Which of the following reaction takes at the cathode in a de-aerated , neutral corrosion environment

• O2 ​+ 2H₂O + 4e⁻⟶ 4OH⁻

• 2H⁺ + 2e⁻⟶ H_2​  

•  2H₂O + 2e− ⟶ 2OH⁻ + H₂​

• 2H₂O + 4e− + 2H⁺ ⟶ 2OH⁻ + 2H_2​  

In differential aeration corrosion

• Poor oxygenated part acts as cathode

• Rich oxygenated part acts as anode

• Poor oxygenated part acts as anode

• Metal as a whole acts as cathode