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Q145 (IAS/2003) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Periodic table elements Answer Verified

Which one of the following statements is not correct?

Result
Your answer: —  Â·  Correct: D
Explanation

Option (4) is not correct. Barium and strontium are not typically found in the free (native) state but occur in minerals—e.g., celestite and other strontium/barium ores—rather than as native metals [4]. The other statements are correct: Plaster of Paris (CaSO4·½H2O) hydrates back to gypsum on mixing with water, and cations such as Na+ accelerate gypsum setting, so NaCl can increase the setting rate [3]. Gypsum is widely used in the cement industry and is added to Portland cement to control/retard the setting of clinker, thus slowing the rate of setting [2]. Alkaline‑earth metals commonly form hydrated salts (e.g., calcium sulfate dihydrate gypsum) as part of their chemistry [5].

Sources

  1. [4] https://pubs.usgs.gov/bul/0540t/report.pdf
  2. [1] Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > Plaster of Paris > p. 33
  3. [3] https://www.govinfo.gov/content/pkg/GOVPUB-C13-5cd6244272fbe7414c372b367c0c4da7/pdf/GOVPUB-C13-5cd6244272fbe7414c372b367c0c4da7.pdf
  4. [2] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 7: Resources > Natural Resources of India > p. 28
  5. [5] https://www.sciencedirect.com/topics/engineering/nuclear-fuel-system
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SIMILAR QUESTIONS

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