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MODEL PAPER - 9 [2026] — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10ScienceMODEL PAPER - 9 [2026]5 Marks
Question
Explain chlor-alkali process and write balanced chemical equations for the reactions that occur. Name the gases obtained at the anode and cathode respectively. Mention two uses each of the two gases obtained in the above process.
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Answer

• Chlor-akali process - When electricity is passed through aqueous solution of sodium chloride (brine), it decomposes toform sodium hydroxide, chlorine and hydrogen.
• $2 NaCl(aq)-2 H_2 O(l) \rightarrow 2 NaOH+Cl_2+H_2$
• Anode - Chlorine gas $/ Cl _2$
• Cathode - Hydrogen gas: $H _2$
• $Cl_2$
1. Used in the preparation of bleaching powder.
2. To make drinking water free from germs or any other.
• $H_{2}$
1. Used in the manufacture of ammonia fertilisers.
2. Used in fuels and margarine.

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