Four different solutions in four different test tubes: Na2SO4, K2CO3, Ni(NO3)2 and Na3PO4.
Solution B and solution C each have pH > 7. Solution C and solution D forms a white precipitate with BaCl2. Solution A forms a black precipitate with H2S.
Identify each of the four solutions.
A is Ni(NO3)2: NiS is formed.
B and C are K2CO3 and Na3PO4: pH > 7 (looked at pKB values).
Then D is Na2SO4: BaSO4 is formed.
How do I distinguish B and C? According to my solubility table, both carbonate and phosphate form insoluble salts with Ba2+.