GATE XE topic:degradation-materials PYQs & Answers

Questions 1–5 of 5. Imported answers require independent review unless marked reviewed.

Discoloration and loss of mechanical strength of plastic chairs exposed to sunlight for several days is due to

Your answerChoose one option.

Hydrophilic degradation

Oxidative degradation

Photo-degradation

Thermal degradation

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Which of the following is/are responsible for pitting corrosion in a metal ?

Your answerSelect all correct options. You can choose more than one.

Rough surface

Grain boundaries

Polished surface

Polymer coated metal surface

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When a metal (M) is immersed in de-aerated acid electrolyte, it polarizes anodically by 0.4 V. The M/M

exchange current density is 10

A m

and Tafel slope is 0.1 V/decade for the anodic reaction. Assume that corrosion is uniform and, anodic and cathodic reactions are under activation control. The rate of metal dissolution in A m

is ________ (round off to 1 decimal place)

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Pilling-Bedworth ratios for oxides of some metals are given in the table.\n\n| Metal | Pilling-Bedworth Ratio |\n|---|---:|\n| Li | 0.57 |\n| Ce | 1.16 |\n| Ta | 2.33 |\n| W | 3.40 |\n\nBased on the criterion of Pilling-Bedworth ratio alone, which one of the following metals will be most protected from high temperature oxidation?

Your answerChoose one option.

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Nickel corrodes at 298 K in a solution of 0.06 M nickel chloride having pH 4. Assuming complete dissociation of nickel chloride, the partial pressure of hydrogen required to stop the corrosion of nickel is _____ atm. (round off to the nearest integer)

(Given: Standard reduction potential of nickel = −0.25 V, Faraday’s constant = 96500 C mol⁻¹, Universal gas constant = 8.314 J K⁻¹ mol⁻¹)

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GATE XE topic:degradation-materials PYQs

How to practice topic:degradation-materials

Question 45

Question 50

Question 22

Question 2

Question 14