Q1. [4]
Common salt is a very important chemical compound for our daily life. It's chemical name is sodium chloride and it is used as a raw material in the manufacture of caustic soda, washing soda, baking soda etc. It is also used in the preservation of pickles, butter, meat etc.
Read the source and answer the questions that follow.
- (i) Name the acid and the base from which common salt can be obtained. [1]
- (ii) State the nature (acidic/basic/neutral) of sodium chloride. Give reason for the justification for your answer. [1]
- (iii) What happens when electric current is passed through an aqueous solution of sodium chloride (called brine)? Name the products obtained along with the corresponding places in the electrolytic cell where each of these products is obtained. [2]
Previously asked in CBSE board exam
2025 31/4/1 Q37
Generated by claude-sonnet-4-6 · 2026-06-15 06:45 · grounding stimulus
Model Answer
(i) Common salt (NaCl) is obtained from hydrochloric acid (HCl) (strong acid) and sodium hydroxide, NaOH (strong base).
(ii) Sodium chloride is neutral in nature. It is formed by the neutralisation of a strong acid (HCl) and a strong base (NaOH), so its aqueous solution has pH = 7.
(iii) When electric current is passed through brine (aqueous NaCl), the process is called chlor-alkali process. The products obtained are:
| Product | Place of collection |
|---|---|
| Chlorine gas (Cl₂) | Anode |
| Hydrogen gas (H₂) | Cathode |
| Sodium hydroxide (NaOH) | Near cathode (in solution) |
Source: Acids, Bases and Salts, Chapter 2 (NCERT Class 10 Science)
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Explanation
- (i) Examiners expect both the name and formula of the acid and base.
- (ii) The key reasoning is "strong acid + strong base → neutral salt." Always state pH = 7.
- (iii) This is a standard 2-mark factual question. Naming all three products AND their correct positions (anode/cathode) is essential to score full marks. Missing the location loses a mark.
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