Electrometallurgy and Corrosion MCQ Questions and Answers

1

Intergrannular corrosion of light 18-8 stainless steel can not be prevented by

A) reducing the carbon content to less than 0.05% B) quenching it from high temperature to prevent chromium carbide precipitation C) adding strong carbide forming elements D) increasing the carbon content

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Answer & Solution

Answer: Option D

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2

Which of the following metals is highest noble in the Galvanic series?

A) Platinum B) gold C) graphite D) titanium

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Answer & Solution

Answer: Option A

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3

Difficult to monitor and very dangerous form of corrosion

A) Galvanic B) Pitting C) Crevice D) Stress

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Answer & Solution

Answer: Option B

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4

Based on the standard galvanic series, select the correct sequence of metals in the increasing order of anodic behaviour:

A) Zn, Fe, Pt, Cu B) Pt, Zn, Cu, Fe C) Fe, Pt, Cu, Zn D) Pt, Cu, Fe, Zn

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Answer & Solution

Answer: Option D

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5

Corrosion of metals involves

A) Physical reactions B) Chemical reactions C) Both A and B D) None of these

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Answer & Solution

Answer: Option B

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6

Match the form of corrosion in Group 1 with the typical examples in Group 2.

Group 1	Group 2
P. Filiform corrosion	1. Austenitic stainless steel in chloride environment
Q. Crevice corrosion	2. Nut bolt with gasket
R. Galvanic corrosion	3. Painted food cans
S. Stress corrosion cracking	4. Steel studs in copper plate

A) P-3, Q-2, R-4, S-1 B) P-1, Q-3, R-4, S-2 C) P-3, Q-4, R-2, S-1 D) P-2, Q-3, R-4, S-1

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Answer & Solution

Answer: Option A

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7

The difference in reversible potential between oxygen reduction reaction and hydrogen evolution reaction of any pH in an aqueous electrolyte is . . . . . . . . volt.
[Given, standard reduction potentials for hydrogen evolution reaction, $$\frac{{{E^ \circ }2{H^ + }}}{{{H_2}}} = OV,SHE$$ and oxygen reduction reaction : $$\frac{{{E^ \circ }{O_2}}}{{4OH}} = 0.4V,SHE.$$ Also PH₂ = PO₂ = 1 atm]

A) 0 B) 0.41 C) 0.82 D) 1.23

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Answer & Solution

Answer: Option D

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8

Zinc rod is immersed in dilute HCl (pure). If a very small amount of FeCl₃ is added to the solution, the corrosion rate of zinc

A) decreases B) increases C) remains constant D) is zero (possivation)

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Answer & Solution

Answer: Option D

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9

Which of these metals can not be electroplated from aqueous electrolyte?

A) Al B) Cu C) Ni D) Zn

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Answer & Solution

Answer: Option A

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10

The oxygen activity in a liquid metal can be-measured by a concentration cell using stabilised zirconia electrolyte PO₂⁽¹⁾ | ZrO₂ based solid electrolyte | PO₂⁽²⁾
Where, PO₂⁽¹⁾ is the reference oxygen pressure and PO₂⁽²⁾ is the oxygen pressure in equilibrium with liquid metal. If, F is Faraday constant, the EMF of the cell is equal to

A) $$ - \frac{{RT}}{{2F}}.\frac{{PO_2^{\left( 2 \right)}}}{{PO_2^{\left( 1 \right)}}}$$ B) $$ - \frac{{RT}}{{4F}}.\frac{{PO_2^{\left( 2 \right)}}}{{PO_2^{\left( 1 \right)}}}$$ C) $$ - \frac{{RT}}{{2F}}In\frac{{PO_2^{\left( 2 \right)}}}{{PO_2^{\left( 1 \right)}}}$$ D) $$ - \frac{{RT}}{{4F}}In\frac{{PO_2^{\left( 2 \right)}}}{{PO_2^{\left( 1 \right)}}}$$

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Answer & Solution

Answer: Option D

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Electrometallurgy and Corrosion MCQ Questions and Answers | Metallurgical Engineering