Module 2 : CORROSION

Rusting is a _____________ process.

• Mechanical

• Chemical

• Physical

• Thermal

Rusting of iron is an example of

• Dry corrosion

• Chemical corrosion

• Electrochemical corrosion

• Galvanic corrosion

Iron rust in the presence of:

• Vacuum

• Moisture

• Oxygen

• Moisture and Oxygen

Chemical formula of RUST is

• FeCO₃

• CUSO₄.5H₂O

• Fe₂O₃. x H₂O

• CaCO₃.2H₂O

What is the chemical nature of rust?

• iron (II) oxide

• Iron (III) chloride

• iron (III) oxide

• hydrated iron(III) oxide

Rusting can be prevented by

• Alloying

• Tinning

• Galvanizing

• All of above

During rusting of iron, reaction occuring at cathode is

• 2 Fe (s)→2 Fe²⁺ + 4 e

• O₂(g) + 4 H⁺(aq) + 4 e ⎯→ 2 H₂O (l )

• 2 Zn (s)→2 Zn²⁺ + 4 e

• 2 Cu (s)→2 Cu²⁺ + 4 e

Corrosion can be prevented by

• Alloying with other elements

• Dehumidification of environment

• Cathodic protection

• All of the above

Which of the following metal would protect iron by cathodic protection

• Silver

• Gold

• Copper

• Magnesium

Which of the following is / are examples of sacrificial protection against rusting?

(1) Iron object coated with tin

(2) Underground iron pipes connected to magnesium bars

(3) Iron railings coated with paint

• (1) only

• (2) only

• (1) and (3) only

• (2) and (3) only