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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. [3] deep thorough-understanding
Ethanol is used as a solvent in many medicines such as tincture iodine, and it is also completely miscible with water. Using your knowledge of ethanol's structure, explain why ethanol can (i) mix with water in all proportions, and (ii) dissolve many organic substances that water cannot dissolve.
Generated by claude-sonnet-4-6 · 2026-06-26 01:11 · grounding rag
Model Answer

Ethanol (C₂H₅OH) has two parts in its structure: a polar –OH (hydroxyl) group and a non-polar hydrocarbon (C₂H₅–) part.

(i) Miscibility with water: The –OH group is similar to water (H–OH) and can form hydrogen bonds with water molecules. This "like dissolves like" interaction allows ethanol to mix with water in all proportions.

(ii) Dissolving organic substances: The non-polar hydrocarbon part of ethanol can interact with non-polar organic substances (which water cannot dissolve, as water is polar). Thus ethanol acts as a bridge solvent, dissolving both polar and non-polar substances.

Source: Chapter 4, Section 4.4.1 — Properties of Ethanol

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Explanation

The examiner expects students to link structure → property. The key concept is the dual nature of ethanol's molecule: the –OH end makes it water-compatible (polar), and the –C₂H₅ end makes it organic-solvent-compatible (non-polar). The textbook directly states ethanol is soluble in water in all proportions and is a good solvent used in medicines. For full marks, both parts (i) and (ii) must be addressed separately. The phrase "like dissolves like" is a useful principle to mention, even if not explicitly in the textbook passage.

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