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Science (086) — AI-generated practice question

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

Q1. [1] medium thorough-understanding
Industrial ethanol is often mixed with small amounts of poisonous substances such as methanol before being sold. (i) What is this process called, and what is the mixture termed? (ii) Why is this done, and which government or industrial body mandates it? (iii) Name one harmful effect of the substance added to ethanol.
  1. A Ethanol is mixed with water to reduce its concentration, making it taste unpleasant.
  2. B Methanol and dyes are added to industrial ethanol to make it poisonous and identifiable, a product called denatured alcohol.
  3. C Industrial ethanol is heated to high temperatures so that it decomposes before it can be consumed.
  4. D Concentrated sulphuric acid is added to industrial ethanol, converting it entirely to ethene gas.
Generated by claude-sonnet-4-6 · 2026-06-26 01:11 · grounding rag
Model Answer

Option B is correct. Methanol and dyes are added to industrial ethanol to make it poisonous and identifiable; this product is called denatured alcohol. Methanol causes blindness and can be lethal even in small quantities.

Source: Chapter 4, Section 4.4.1 (Properties of Ethanol)

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Explanation

Although this question has three sub-parts, it is a 1-mark MCQ, so you only need to identify the correct option and briefly justify it. Option B matches the passage directly: the process is denaturation, the product is denatured alcohol, it is done to prevent misuse, and methanol (the added substance) affects the optic nerve causing blindness. The other options describe unrelated reactions (dehydration, oxidation, dilution) and are not supported by the passage.

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