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Q82 (NDA-II/2012) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Basic chemical principles Answer Verified

Which one among the following is a double salt?

Result
Your answer: —  Â·  Correct: B
Explanation

A double salt is a substance formed by the combination of two different salts that crystallize together in a fixed ratio but dissociate into their constituent ions when dissolved in water. Option 2, K2SO4·Al2(SO4)3·24H2O, commonly known as potash alum, is a classic example of a double salt consisting of potassium sulphate and aluminium sulphate [1]. Unlike complex salts like potassium ferrocyanide (K4[Fe(CN)6]), which retain their complex ion structure in solution [1], double salts lose their identity in aqueous form. Option 3, CuSO4·5H2O (copper sulphate pentahydrate), is a simple hydrated salt, and Option 4, NaCl (sodium chloride), is a simple salt [3]. Potash alum belongs to the 'alum' family of double sulphates, which are typically isomorphous and follow the general formula of M2SO4·M'2(SO4)3·24H2O.

Sources

  1. [1] https://uou.ac.in/sites/default/files/slm/BSCCH-204.pdf
  2. [3] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 8: Nature of Matter: Elements, Compounds, and Mixtures > 8.3.2 Compounds > p. 124
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SIMILAR QUESTIONS

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Which one among the following is not a property of salt?

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When aqueous solutions of two salts are mixed, the third salt formed may appear as a solid precipitate or a clear solution depending upon the solubility of its ions. It is observed that all salts of Na, K, NH4 are soluble. All nitrates and bicarbonates are also soluble. All halides (chlorides, bromides, iodides) are soluble except those of Ag, Hg (I) and Pb. All sulphates are soluble except those of Ag, Ca, Ba and Pb. Which one among the following combinations of solutions will produce a solid precipitate?

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Which one among the following is a chemical process?