UPSC Prelims 1999·GS1·science-and-technology·materials and robotics

Consider the following statements: Glass can be etched or scratched by I. diamond. II. hydrofluoric acid. III. aquilegia. IV. cone, sulphuric acid. Which of these statements are correct?

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Last updated 23 May 2026, 3:31 pm IST
  1. AI and IV
  2. BII and III
  3. CI and IICorrect
  4. DII and IV

Explanation

The correct option is C because of the following reasons: Statement I is correct because diamond is the hardest natural substance known. Due to its extreme hardness, it can easily scratch the surface of glass, which is why it is commonly used in industrial glass cutters. Statement II is correct because hydrofluoric acid is one of the few acids that can chemically react with silicon dioxide, the main component of glass. This chemical reaction dissolves the glass surface, a process known as etching. Statement III is incorrect because aquilegia is a genus of flowering plants, commonly known as columbine, and has no properties that can etch or scratch glass. Statement IV is incorrect because concentrated sulphuric acid does not react with silicon dioxide at room temperature and therefore cannot etch glass. Since only statements I and II are accurate, option C is the right answer.
science-and-technology: Consider the following statements: Glass can be etched or scratched by I. diamond. II. hydrofluoric acid. III. aquilegia
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