Select the correct statement(s):

Options

A. Normal and polysulphides of ailkali metals are soluble in water
B. The sulphides of aluminum and magnesium can only be prepared under dry condition as they are completely hydroysed by water
C. When filter paper is moistened with a solution of sodium miropressium made alkline with sodium hydroxide or ammonia solution , a purple colouration is produced with free hydrogen sulphide
D. Thiosulphate salt of `Pb,Ag and Ba ` are insoluble and dissolve in excess of sodium thisulphide solution forming thiosulphde.

Answer

To solve the question regarding the correct statements about sulfides and thiosulfates, we will analyze each option step by step:

### Step 1: Analyze Option 1
**Statement:** Normal and polysulfides of alkali metals are soluble in water.

**Analysis:**
- Alkali metal sulfides (like Na2S) are indeed soluble in water.
- When Na2S is dissolved in water, it can form NaHS and further react to produce H2S gas and NaOH.
- Therefore, this statement is **correct**.

### Step 2: Analyze Option 2
**Statement:** The sulfides of aluminium and magnesium can only be prepared under dry conditions as they are completely hydrolyzed by water.

**Analysis:**
- It is known that aluminum and magnesium sulfides are prepared at high temperatures (greater than 1100°C) to avoid hydrolysis.
- If water is present, these sulfides will hydrolyze, making it necessary to prepare them under dry conditions.
- Thus, this statement is **correct**.

### Step 3: Analyze Option 3
**Statement:** When filter paper is moistened with a solution of sodium nitroprusside, then the NaOH or ammonia solution produces a purple coloration with free hydrogen sulfide.

**Analysis:**
- When sodium sulfide (Na2S) reacts with sodium nitroprusside, it forms a violet-colored complex (Na4Fe(CN)5NOS).
- The presence of hydrogen sulfide leads to this purple coloration.
- Therefore, this statement is **correct**.

### Step 4: Analyze Option 4
**Statement:** Thiosulfate salts of lead, silver, and barium are insoluble and dissolve in excess sodium thiosulfide solution forming thiosulfide.

**Analysis:**
- The sulfides of lead, silver, and barium are generally insoluble in water but can dissolve in excess sodium thiosulfide.
- However, the statement incorrectly suggests that they are insoluble and form thiosulfide, which is misleading.
- The correct interpretation is that they dissolve in sodium thiosulfide, but they are not thiosulfides themselves.
- Thus, this statement is **incorrect**.

### Conclusion
The correct statements are:
- Option 1: Correct
- Option 2: Correct
- Option 3: Correct
- Option 4: Incorrect

### Final Answer
The correct options are 1, 2, and 3.

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