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A white crystalline substance dissolves ...

A white crystalline substance dissolves in water.On passing `H_(2)S` in this solution, a black precipitate is obtained.The black precipitate dissolves completely in hot `HNO_(3)`.On adding a few drops of concentrated `H_(2)SO_(4)`, a white precipitate is obtained.This precipitate is that of

A

`BaSO_(4)`

B

`SrSO_(4)`

C

`PbSO_(4)`

D

`CdSO_(4)`

Text Solution

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To solve the problem step-by-step, we will analyze the given information and reactions involved. ### Step 1: Identify the initial substance The problem states that we have a white crystalline substance that dissolves in water. This indicates that the substance is likely a soluble salt. **Hint:** Consider common white crystalline salts that are soluble in water. ### Step 2: Reaction with H2S When H2S is passed through the solution, a black precipitate is formed. This suggests that the white crystalline substance contains a metal ion that can react with H2S to form a sulfide, which is typically black. **Hint:** Look for metal ions that form black sulfides when reacted with H2S. ### Step 3: Identify the black precipitate The black precipitate formed upon passing H2S is likely lead(II) sulfide (PbS), as it is known to be black. **Hint:** Recall the common sulfides formed by metal ions and their colors. ### Step 4: Dissolution in hot HNO3 The black precipitate (PbS) dissolves completely in hot HNO3. This reaction indicates that PbS is being oxidized to lead(II) nitrate (Pb(NO3)2), along with the release of sulfur and other gases. **Hint:** Consider the reactions of sulfides with strong oxidizing agents like nitric acid. ### Step 5: Reaction with concentrated H2SO4 Upon adding a few drops of concentrated H2SO4 to the solution containing Pb(NO3)2, a white precipitate is formed. This white precipitate is likely lead(II) sulfate (PbSO4). **Hint:** Identify the common precipitates formed when sulfate ions react with metal ions. ### Conclusion The white precipitate obtained after adding concentrated H2SO4 is lead(II) sulfate (PbSO4). Therefore, the answer to the question is: **The precipitate is PbSO4.** ---
To solve the problem step-by-step, we will analyze the given information and reactions involved. ### Step 1: Identify the initial substance The problem states that we have a white crystalline substance that dissolves in water. This indicates that the substance is likely a soluble salt. **Hint:** Consider common white crystalline salts that are soluble in water. ### Step 2: Reaction with H2S ...
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