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JAMB Chemistry 1985 Question 48

Question 48

Qualitative Analysis

An aqueous solution of an inorganic salt gave white precipitate (i) soluble in excess aqueous NaOH (ii) insoluble in excess aqueous NH3 (iii) with dilute HCl. The cation present in the inorganic salt is

  1. A.NH4+
  2. B.Ca2+
  3. C.Zn2+
  4. D.Al3+
  5. E.Pb2+.
Show the answer and explanation

Answer: E (Pb2+.)

Explanation

Lead (II) ions give a white Pb(OH)2 precipitate that dissolves in excess NaOH but not in excess ammonia, and dilute HCl gives white lead (II) chloride. Al3+ gives no precipitate with HCl.