Chemistry - Salt Analysis Question with Solution | TestHub
Number of correct statements among the following.
(i) White ppt. of & are soluble in dil. , dil. HCl & .
(ii) White ppt. of on standing converts to another white ppt. which acquires a colour in presence of aq.
(iii) All alkali metal bicarbonates are soluble.
(iv) Addition of followed by heating aqueous suspension can distinguish and solutions.
(v) solution gives same observation as with slightly alkaline dmg solution.
(vi) on treatment with in acidic medium gives a black ppt.
Answer:
Solution:
Statement (i) is correct because barium carbonate (BaCO₃) and calcium carbonate (CaCO₃) are salts of a weak acid (H₂CO₃), making them readily soluble in dilute strong acids like HNO₃ and HCl, as well as weak acids like acetic acid (CH₃COOH).
Statement (ii) is correct because barium sulfite (BaSO₃) slowly oxidizes in air to form barium sulfate (BaSO₄), which is another white precipitate that turns pink/purple in the presence of aqueous potassium permanganate (KMnO₄).
Statement (vi) is correct because sodium hexahydroxostannate(IV), formed by reacting with bismuth chloride (BiCl₃), undergoes a redox reaction in an acidic/alkaline medium to reduce Bi³⁺ ions into metallic bismuth, appearing as a distinct black precipitate.
The remaining statements are incorrect because not all alkali metal bicarbonates are highly soluble (e.g., NaHCO₃ has low solubility), AgNO₃ gives different heat test precipitates for thiosulfate and sulfite, and Fe²⁺ does not give the same bright red complex with dimethylglyoxime (dmg) as Ni²⁺ does.
