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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] deep exam-ready
Assertion (A): Optical density and mass density of a medium always increase together. Reason (R): Kerosene has a higher refractive index than water but has a lower mass density than water.
  1. A Both A and R are true, and R is the correct explanation of A.
  2. B Both A and R are true, but R is NOT the correct explanation of A.
  3. C A is false and R is true.
  4. D Both A and R are false.
Generated by claude-sonnet-4-6 · 2026-06-26 01:12 · grounding rag
Model Answer

Answer: C

Assertion (A) is false — optical density and mass density do not always increase together. Reason (R) is true — kerosene has a higher refractive index (1.44) than water (1.33), making it optically denser, yet its mass density is lower than water.

Explanation

The textbook explicitly states: "an optically denser medium may not possess greater mass density — kerosene having higher refractive index is optically denser than water, although its mass density is less than water." So Assertion A is false (the two densities are independent), while Reason R correctly states a fact from Table 9.3. Option C is correct.

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