The mass of a substance deposited at the cathode is directly proportional to the:
A. Current
B. Quantity of electricity passed
C. All of the above
D. Time
Answer: Option C
Solution (By JKExamLibrary)
According to Faraday's First Law of Electrolysis, the mass (m) of a substance deposited at an electrode is directly proportional to the total quantity of electricity (Q) passed through the electrolyte. Since Q = Current (I) × Time (t), the mass is directly proportional to both the current and the time.
Explanation:
Salt is obtained by evaporation of seawater in shallow ponds. Water evaporates leaving salt behind. Filtration cannot separate dissolved salt. Distillation would give pure water, not salt. Sublimation for sublimable solids.
Explanation:
Lead-acid battery uses dilute sulfuric acid (H₂SO₄) as the electrolyte with lead dioxide (PbO₂) as positive plate and spongy lead (Pb) as negative plate. Discharge reaction: Pb + PbO₂ + 2H₂SO₄ → 2PbSO₄ + 2H₂O. It is a secondary (rechargeable) battery used in automobiles. The specific gravity of electrolyte indicates the state of charge. KOH is used in Ni-Cd and alkaline batteries.
Explanation:
In K2Cr2O7, potassium has an oxidation state of +1 and oxygen is -2. Let the oxidation state of Cr be x. The sum of oxidation states in a neutral molecule is zero: 2(+1) + 2(x) + 7(-2) = 0. Solving this gives 2 + 2x - 14 = 0, so 2x = 12, and x = +6.
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