Sodium hydroxide is manufactured by the electrolysis of brine (NaCl solution). Which gas is produced at the anode? MCQ with Answer and Explanation

Sodium hydroxide is manufactured by the electrolysis of brine (NaCl solution). Which gas is produced at the anode?
A. Hydrogen
B. Nitrogen
C. Chlorine
D. Oxygen
Answer: Option C
Solution (By JKSSB Mock Tests)
In chlor-alkali process (electrolysis of concentrated NaCl solution), Cl⁻ ions are oxidized at the anode: 2Cl⁻ → Cl₂(g) + 2e⁻ (chlorine gas). At the cathode, H₂O is reduced: 2H₂O + 2e⁻ → H₂(g) + 2OH⁻, producing hydrogen gas and leaving NaOH in solution. The process uses a diaphragm or membrane cell to keep products separate. Chlorine is used for water treatment and PVC.

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Question #1
A catalyst that slows down a reaction is known as:
A. Autocatalyst
B. Inhibitor
C. Activator
D. Promoter

Correct Answer: Option B


Explanation:
Inhibitors (negative catalysts) decrease reaction rate. Promoters enhance activity of a catalyst; activators increase effectiveness; autocatalysts are reaction products that catalyze the reaction.

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Question #2
The reduction of a metal oxide by carbon at high temperature is known as:
A. Smelting
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Correct Answer: Option A


Explanation:
Smelting is the pyrometallurgical process of extracting a metal from its ore by heating it beyond its melting point and reducing the metal oxide with a carbonaceous reducing agent (like coke or coal). Flux is often added to remove impurities as slag. Calcination and roasting are oxidation processes.

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Which of the following hydrocarbons is an unsaturated compound?
A. C₄H₁₀
B. C₃H₈
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Correct Answer: Option C


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