Engineering Chemistry Multiple Choice Questions on “Galvanic Series”.
1. Galvanic series gives real and useful information regarding the ____________
a) Electrical conductivity of metals and alloys
b) Thermal conductivity of metals and alloys
c) Corrosion behaviour of metals and alloys
d) Oxidation power of metals and alloys
Answer: c
Clarification: Galvanic series gives real and useful information regarding the corrosion behaviour of metals and alloys in a given environment, i.e. which metal will corrode at a faster rate and which will not corrode at all.
2. Which of the following is the most noble metal?
a) Gold
b) Graphite
c) Titanium
d) Platinum
Answer: d
Clarification: Platinum is the most noble metal present at the protected end of galvanic series. It does not corrode easily.
3. Which of the following is the least noble metal?
a) Magnesium
b) Brass
c) Aluminium
d) Nickel
Answer: a
Clarification: Magnesium is the least noble metal present at the corroded end of the galvanic series. It corrodes very easily and at very fast rate.
4. Arrange the following in the ascending order of their degree of corrosion.
a) Zinc >> Magnesium >> Copper >> Lead >> Aluminium
b) Copper >> Lead >> Aluminium >> Zinc >> Magnesium
c) Zinc >> Magnesium >> Lead >> Copper >> Aluminium
d) Copper >> Aluminium >> Zinc >> Lead >> Magnesium
Answer: b
Clarification: The correct order is Copper >> Lead >> Aluminium >> Zinc >> Magnesium. Magnesium is the most active towards corrosion and copper is the least active towards corrosion among the given elements.
5. As the distance between the two metals increases in the galvanic series, the degree of corrosion ____________
a) Increases
b) Decreases
c) Remains same
d) First increases then decreases
Answer: a
Clarification: As the distance between the two metals increases in the galvanic series, the degree of corrosion increases. elements are arranged in the decreasing order of corrosion in the galvanic series.
6. Which of the following metals are protected metals?
a) Present at the top
b) Present at the middle
c) Present at the bottom
d) Both present at the top and the bottom
Answer: c
Clarification: The metals which are present at the bottom of the galvanic series are the protected metals. These are the least active towards corrosion and hence also called noble or protected metals.
7. Which electrode is used for measuring electrode potential as a standard electrode in galvanic series?
a) Hydrogen electrode
b) Calomel electrode
c) Oxygen electrode
d) Nitrogen electrode
Answer: b
Clarification: Calomel electrode is used for measuring electrode potential as a standard electrode in galvanic series. it gives the value of electrode potential of different electrodes.
8. The galvanic series predicts the relative displacement tendencies of metals and non-metals in electrolytes containing a particular concentration of salts.
a) True
b) False
Answer: b
Clarification: The galvanic series predicts the corrosion tendencies of metals and non-metals in the actual environment. It has been drawn up for metals and alloys in sea water, which shows their relative nobility.
9. The phenomenon by which a metal or alloy show high corrosion resistance due to the formation of the highly protective film is called ____________
a) Electrolysis
b) Electrodialysis
c) Galvanisation
d) Passivation
Answer: d
Clarification: The phenomenon by which a metal or alloy shows high corrosion resistance due to the formation of the highly protective film is called passivation. Passivation is the use of a light coat of protective material, such as metal oxide, to create a shell against corrosion.
10. The thickness of the protective film in passivation is about ____________
a) 1 mm
b) 0.02 mm
c) 0.0004 mm
d) 0.004 mm
Answer: c
Clarification: The thickness of the protective film in passivation is about 0.0004 mm. Passivation is the use of a light coat of protective material, such as metal oxide, to create a shell against corrosion.