Among the electrolytes `Na_(2),SO_(4),CaCl_(2),Al_(2)(SO_(4))_(3) and NH_(4)Cl`, the most effective coagulating agent for `Sb_(2)S_(3)` sol is

Options

A. `Na_(2)SO_(4)`
B. `CaCl_(2)`
C. `Al_(2)(SO_(4))_(3)`
D. `NH_(4)Cl`

Explanation

To determine the most effective coagulating agent for the `Sb2S3` sol among the given electrolytes (`Na2SO4`, `CaCl2`, `Al2(SO4)3`, and `NH4Cl`), we can follow these steps:

### Step 1: Identify the nature of the sol
`Sb2S3` is a negatively charged colloidal sol. This means that to coagulate it, we need a positively charged ion that can neutralize the negative charge of the sol.

**Hint:** Remember that coagulation occurs when oppositely charged ions neutralize the charge of the colloidal particles.

### Step 2: Analyze the electrolytes
We will analyze the electrolytes based on the charge of their cations:
- `Na2SO4` dissociates into `2Na^+` and `SO4^2-`.
- `CaCl2` dissociates into `Ca^2+` and `2Cl^-`.
- `Al2(SO4)3` dissociates into `2Al^3+` and `3SO4^2-`.
- `NH4Cl` dissociates into `NH4^+` and `Cl^-`.

**Hint:** Focus on the cations of each electrolyte, as they will determine the coagulating power.

### Step 3: Determine the charge and valency of cations
The cations and their charges are:
- `Na^+` (valency = 1)
- `Ca^2+` (valency = 2)
- `Al^3+` (valency = 3)
- `NH4^+` (valency = 1)

**Hint:** Higher valency cations have a greater coagulating power due to their ability to neutralize more negative charges.

### Step 4: Apply Hardy-Schulze Rule
According to the Hardy-Schulze rule, the coagulating power of an electrolyte is directly proportional to the valency of the active ion. Therefore, the order of coagulating power based on the cations is:
1. `Al^3+` (highest coagulating power)
2. `Ca^2+`
3. `Na^+`
4. `NH4^+`

**Hint:** The greater the charge of the cation, the more effective it is at coagulating the negatively charged sol.

### Step 5: Conclusion
Since `Al^3+` from `Al2(SO4)3` has the highest valency among the cations, it will be the most effective coagulating agent for `Sb2S3` sol.

Thus, the most effective coagulating agent for `Sb2S3` sol is **`Al2(SO4)3`**.

**Final Answer:** `Al2(SO4)3` (Option C)