This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Electroplating Baths – 1”.
1. Identify the electrolyte in sodium arsenide plating.
a) Arsenide solution
b) Arsenide salt solution
c) Arsenide metal
d) Salt solution
Explanation: During the process of electroplating, impure metal is kept as anode and pure metal is kept as a cathode. Also for the diffusion of ions to take place, an electrolytic solution is needed which is nothing but metal salt solution (that is arsenide salt solution).
2. Identify the electrolyte in chromium deposition.
a) Potassium chromate solution
b) Red chromate
c) Chromium sulphide
d) Yellow chromate
Explanation: Since from the above four options, charge carriers diffuse more rapidly through potassium chromate solution (though all the four solutions can be electrolytes). The reason is potassium chromate is alkaline is nature and allows the free flow of electrons.
3. What is anode mud?
a) Impurity found below anode after plating
b) Impurity which can separated from the mixture using filtration
c) Impurity which cannot be separated
d) Distilled impurity
Explanation: During electroplating of noble materials, some electrons may shift toward the pure materials resulting in the deposition of its ore components. Usually, anode muds are basically noble metals like zinc, silver etc.
4. How can anode mud be removed?
Explanation: Since anode mud is nothing but noble metals, they do not mix with the electrolyte (they form heterogeneous solution with them). Hence they can be removed easily by using the process called filtration.
5. Can a non-metal be used as an electrolyte?
a) No because they form immiscibility with the main material
b) Yes because they have high discharge capacity
c) No because they are poor conductors of electricity
d) Yes because they have retentivity
Explanation: Since the main principle of electroplating is a passage of current, only metal electrolytes will have the ability to make charges flow and hence non-metals cannot be used.
6. Identify the anode mud in the separation of gold from its ore.
d) Silver and Zinc
Explanation: Since the ore of gold contains other noble materials like tin, aluminium, magnesium etc, the most commonly and abundantly available materials are only zinc and silver (65 and 43% respectively).
7. Identify the type of electrolyte: NaCl, acetic acid.
a) Strong, Weak
b) Weak, Strong
c) Strong, Strong
d) Weak, Weak
Explanation: Since NaCl dissociates completely in water (that is it gives the correct proportion of H+ and OH-
ions respectively) whereas acetic acid fails to do so. Hence they are strong and weak electrolytes respectively.
8. Identify the strong electrolytes from the following.
a) NaCl, CaCl
b) Acetic acid, CaCl
c) CaCl, citric acid
Explanation: Since NaCl and CaCl dissociates completely in water (that is it gives the correct proportion of H+ and OH- ions respectively) whereas acetic acid fails to do so. Hence NaCl and CaCl are strong electrolytes.
9. What is the life span of a general metal electrolyte?
a) 1 hour
b) 2 hours
c) 3 hours
d) 5 hours
Explanation: After the process of electroplating, the electrolyte can stay up to a time period of 3 hours and then it would decay automatically. This process of decay of electrolyte is called decomposition.
10. Who discovered electroplating?
a) Luigi Brugnatelli
b) Thomas Kennedy
c) Johansen Mathews
d) Mariana Simsons
Explanation: Luigi Brugnatelli got the idea of electroplating in the late 80’s when he first discovered that metals can transform electricity from one form to another within themselves. This idea led to the evolution of electroplating.
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