Answer: we could tell Ca(NO3)2 and Zn(NO3)2 apart from their reactions with KOH and Na2C2O4, based on the color of the precipitate formed and the speed which each precipitate is formed. Also, a reaction with NaOH could be used and the solubility of the formed precipitate in excess NaOH could also be used to differentiate Ca(NO3)2 and Zn(NO3)2.
Step-by-step explanation:
The question requires us to determine how to tell apart solutions of Ca(NO3)2 and Zn(NO3)2, based on the table of informations provided.
(General topic: Solutions)
According to the table provided by the question, both Ca(NO3)2 and Zn(NO3)2 do not react with KI and Na2SO4 (we could also say that the reaction of Ca(NO3)2 and Zn(NO3)2 with KI or Na2SO4 do not produce any changes that we can identify). On the other side, the reaction of these nitrate salts with KOH and Na2C2O4 produce precipitates with similar characteristics (all of them are white precipitate, with small differences among them).
We could differentiate Ca(NO3)2 from Zn(NO3)2 based on these characteristics:
1) The color of precipitates formed when reacting the nitrate salts with KOH is slightly different (faint white for calcium nitrate and milky white for zinc nitrate). Also, the reaction between Ca(NO3)2 and KOH is slower, then the precipitate formed when reacting Zn(NO3)2 with KOH would form faster;
2) Similarly, the color of the precipitates formed when reacting the nitrate salts with Na2C2O4 are sloghtly different and the reaction of Zn(NO3)2 with Na2C2O4 is slower, therefore the precipitate formed in this reaction would be produced slower (or wouldn't be observed due to the slow reaction);
3) Additionally, when reacting Ca(NO3)2 with NaOH, a precipitate that is insoluble in excess of NaOH would be formed, while when reacting Zn(NO3)2 with NaOH, a precipitate would initially be formed, but it would dissolve in excess of NaOH.
Therefore, we could tell Ca(NO3)2 and Zn(NO3)2 apart from their reactions with KOH and Na2C2O4, based on the color of the precipitate formed and the speed which each precipitate is formed. Also, a reaction with NaOH could be used and the solubility of the formed precipitate in excess NaOH could also be used to differentiate Ca(NO3)2 and Zn(NO3)2.