Which electrolyte is used in the electroplating of silver?
A. NaCl solution
B. AgNO₃ solution
C. CuSO₄ solution
D. AgCl solution
Answer: Option B
Solution (By JKSSB Mock Tests)
For silver electroplating, the electrolyte is typically a solution of silver cyanide (AgCN) in excess potassium cyanide or silver nitrate (AgNO₃). AgNO₃ with proper complexing agents can be used. CuSO₄ is for copper plating. NaCl is not suitable. The anode is pure silver, cathode is the article. Silver ions migrate to cathode and are reduced to metal.
Explanation:
Gypsum (CaSO₄·2H₂O) is added to clinker to control the rapid reaction of tricalcium aluminate with water, which would otherwise cause flash (quick) setting. Gypsum slows down the hydration of C₃A, thus increasing the setting time and allowing workability. Without gypsum, cement would set almost immediately upon mixing with water, making placement impossible.
Explanation:
Permanent hardness (due to CaSO₄ etc.) can be removed by adding Na₂CO₃, which precipitates CaCO₃. Boiling only removes temporary hardness. Ion exchange and calgon also work.
Explanation:
Fajan's rules state that covalent character in an ionic bond increases with greater polarizing power of the cation and greater polarizability of the anion. A small cation has high charge density (high polarizing power), and a large anion has loosely held outer electrons (high polarizability), favoring covalency.
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