Question

Which of the following factors promote corrosion?

• A. Reactivity of metal
• B. Presence of air and moisture
• C. Presence of electrolytes
• D. Strains in metals

Answer 1

Answer: (A), (B), (C), (D)

Strains in metals

Factors which promote corrosion:
a. Reactivity of the metal. More active metals are readily corroded.
b. Presence of impurities. Presence of impurities in metals enhance the chances of corrosion. Pure metals do not corrode, e.g., pure iron does not rust.
c. Presence of air and moisture. Air and moisture accelerate corrosion. Presence of gases such as $S{O}_{2}andC{O}_2$ in air catalyze the process of corrosion. Iron when placed in vacuum does not rust.
d. Strains in metals. Corrosion (e.g., rusting of iron) takes place rapidly at bends, scratches, nicks, and cuts in the metal.
e. Presence of electrolytes. Electrolytes, if present, also increase the rate of corrosion. For example, iron rusts faster in saline water than in pure water.