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Science — AI-generated practice question

AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.

Q1. [1] straightforward initial-understanding
The chemical formula of washing soda is: (a) Na₂CO₃ (b) NaHCO₃ (c) Na₂CO₃·10H₂O (d) NaCl
  1. a Na₂CO₃
  2. b NaHCO₃
  3. c Na₂CO₃·10H₂O
  4. d NaCl
Generated by claude-sonnet-4-6 · 2026-06-17 12:36 · grounding rag
Model Answer

(c) Na₂CO₃·10H₂O

Washing soda is sodium carbonate decahydrate with the chemical formula Na₂CO₃·10H₂O.

Source: Chapter 2, Section 2.4.3

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Explanation

The key distinction here is between Na₂CO₃ (anhydrous sodium carbonate) and Na₂CO₃·10H₂O (washing soda, which contains 10 water molecules of crystallisation). NaHCO₃ is baking soda — a common distractor. Examiners specifically test whether students know the water of crystallisation (·10H₂O) is part of the formula for washing soda.

Previous-year CBSE Grade 10 board exam questions, organised by subject and chapter, each with a model answer — free to read and print.