Final answer:
K₃PO₄, or Potassium phosphate, is the compound among the given options that is soluble in water, according to common solubility rules.
Step-by-step explanation:
The question asks which of the following compounds is soluble in water: Ni(OH)₂, K₃PO₄, BaSO₄, CoCO₃, PbCl₂. Based on solubility rules, we know:
- Ni(OH)₂ (Nickel(II) hydroxide) is generally insoluble.
- K₃PO₄ (Potassium phosphate) is soluble
- BaSO₄ (Barium sulfate) is insoluble (as confirmed by provided reference information).
- CoCO₃ (Cobalt(II) carbonate) is generally insoluble.
- PbCl₂ (Lead(II) chloride) is soluble in hot water but only slightly soluble in cold water.
Therefore, the compound that is soluble in water among the given choices is K₃PO₄.