This set of Engineering Chemistry test focuses on “Factors Influencing Corrosion”.
1. Which of the following factor influences the rate and extent of corrosion?
a) Nature of metal only
b) Nature of the environment only
c) Both nature of metal and environment
d) Nature of reaction
Explanation: Both nature of metal and environment influences the rate and extent of corrosion as corrosion is a natural process, which converts a refined metal to a more stable form, such as its oxide, hydroxide, or sulfide.
2. Which of the following is not associated with the nature of metal?
a) Nature of oxide film
b) Nature of electrolyte
d) Physical state
Explanation: Nature of metal includes its purity, physical state, nature of oxide film, position in galvanic series, etc and hence it is not associated with the nature of electrolyte.
3. Which of the following is not associated with the nature of the environment?
c) Effect of pH
d) Volatility of corrosion products
Explanation: Nature of environment includes temperature, humidity, effect of pH, nature of electrolyte, etc and hence volatility of corrosion product is not associated with it.
4. Lesser is the purity of the percentage of metal, faster is the rate of corrosion.
Explanation: Lesser is the purity of the percentage of metal, faster is the rate of corrosion. Pure metals does not corrose easily whereas impure metals corrode easily.
5. Rate of corrosion of anodic region is inversely proportional to the
a) Cathodic area
b) Anodic area
c) Product of anodic area and cathodic area
d) Sum of anodic area and cathodic area
Explanation: Rate of corrosion of anodic region is inversely proportional to the anodic area. Greater will be the anodic area, faster will be the corrosion at an anode.
6. Corrosion of zinc can be minimized by increasing the pH to
Explanation: Corrosion of zinc can be minimized by increasing the pH to 11. pH 11 means it will be basic in nature and hence will be less prone to corrosion.
7. Which of the following medium is most corrosive?
d) Both acidic and basic
Explanation: Acidic medium is more corrosive than alkaline and neutral media. In acidic medium, metals are more reactive and more prone to corrosion.
8. Which of the following is an example of an inactive atmospheric suspended particle?
b) (NH4)2 SO4
Explanation: Charcoal is an example of an inactive atmospheric suspended particle. Charcoal is obtained by removing water and other volatile constituents from animal and vegetation substances.
9. Excessive corrosion of metal takes place if corrosion product is
c) Both volatile as well as non-volatile
d) Initially volatile and then non-volatile
Explanation: Excessive corrosion of metal takes place if corrosion product is volatile. When the corrosion product is volatile it easily escapes with gases and hence allowing more metal to corrode.
10. The specific volume ratios of W, Cr and Ni are 3.6, 2.0 and 1.6 respectively. Which of them will have the least rate of corrosion?
d) All will have the same rate of corrosion
Explanation: W will have the least rate of corrosion, even at higher temperatures because the specific volume ratio is inversely proportional to the rate of corrosion.
Sanfoundry Global Education & Learning Series – Engineering Chemistry.
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