Final answer:
In water, potassium thiocyanate dissolves into potassium and thiocyanate ions. From the given options, only NiCl2 is soluble in water based on common solubility rules, whereas Fe(OH)3, AgSO4, PbCrO4, and MgPO4 are insoluble.option (c).
Step-by-step explanation:
The dissociation reaction for the ionic compound potassium thiocyanate (KSCN) in water is as follows:
KSCN(s) → K+(aq) + SCN−(aq)
Using the solubility rules mentioned, the soluble compounds at room temperature from the list provided would be:
- NiCl2 (Nickel(II) chloride is generally soluble as chlorides tend to be soluble)
The others are generally insoluble based on common solubility rules:
- Fe(OH)3 (Iron(III) hydroxide precipitates as hydroxides are usually not soluble except for those of alkali metals and some alkaline earth metals)
- AgSO4 (Silver sulfate is slightly soluble, but generally not considered soluble)
- PbCrO4 (Lead(II) chromate precipitates as both lead(II) and chromate compounds tend to form insoluble compounds)
- MgPO4 (Magnesium phosphate precipitates as phosphates are typically insoluble except with alkali metals)