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JAMB Chemistry 2008 Question 35

Question 35

Qualitative Analysis

When a solution of ammonium trioxocarbonate(IV) is added to a solution of an unknown salt, a white precipitate which is soluble in dilute hydrochloric acid but insoluble in ethanoic acid is formed. This indicates the presence of

  1. A.Ca2+
  2. B.Na+
  3. C.Zn2+
  4. D.K+
Show the answer and explanation

Answer: A (Ca2+)

Explanation

Ammonium carbonate precipitates calcium as white CaCO3, which dissolves in dilute HCl. Na+ and K+ carbonates are soluble, and the zinc precipitate redissolves in excess ammonium salt.