The answer is A.
A pure substance is pure, so it cannot be separated in most cases.
BaSO₄ is relatively harmless, but BaS is highly toxic.
BaSO₄ is quite insoluble (240 µg/100 mL). It is a <em>mild irritant</em> in cases of skin contact and inhalation. However, it is <em>safe enough</em> that health professionals ask patients to drink a suspension of BaSO₄. The Ba is opaque to X-rays, so it makes the stomach and intestines more visible to radiographers.
BaS is soluble (7.7 g/100 mL). It reacts slowly with water and more rapidly in the acid conditions of the stomach to <em>release H₂S</em>.
BaS + 2HCl ⟶ BaCl₂ + H₂S
An H₂S concentration of 60 mg/100 mL can be <em>fatal within 30 min</em>.
<em>Don’t eat barium sulfide!</em>
Maybe sodium? becasue its an element and I would like some points... sorryy:((((
