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JAMB Chemistry 1985 Question 19

Question 19

Chemical Formulae and Equations

What is the formula of sodium gallate if gallium (Ga) shows an oxidation number of + 3?

  1. A.NaGaO3
  2. B.Na2Ga(OH)2
  3. C.NaGa(OH)3
  4. D.NaGa(OH)4
  5. E.NaGaO.
Show the answer and explanation

Answer: D (NaGa(OH)4)

Explanation

In NaGa(OH)4: (+1) + Ga + 4(−1) = 0, so Ga = +3. Gallium is in the same group as aluminium, which forms NaAl(OH)4.