which compound is insoluble in water?\n1. baso₄\n2. cacro₄\n3. kclo₃\n4. na₂s

Brief Explanations:

To determine which compound is insoluble in water, we use solubility rules:

• Sulfates ($\ce{SO_4^{2-}}$): Most sulfates are soluble, but exceptions include $\ce{BaSO_4}$, $\ce{PbSO_4}$, $\ce{CaSO_4}$ (slightly soluble), etc. So $\ce{BaSO_4}$ is insoluble.
• Chromates ($\ce{CrO_4^{2-}}$): Most chromates are insoluble, but $\ce{CaCrO_4}$ is soluble (calcium chromate has moderate solubility in water).
• Chlorates ($\ce{ClO_3^{-}}$): All chlorates are soluble, so $\ce{KClO_3}$ is soluble.
• Sulfides ($\ce{S^{2-}}$): Most sulfides are insoluble, but alkali metal sulfides (like $\ce{Na_2S}$) are soluble.

Answer:

1. $\ce{BaSO_4}$