Which of the following has minimum flocculation value :-

Options

A. `Pb^(2+)`
B. `Pb^(4+)`
C. `Sr^(2+)`
D. `Na^(+)`

Answer

To determine which of the given options has the minimum flocculation value, we can follow these steps:

### Step 1: Understand Flocculation Value
Flocculation value refers to the minimum concentration of an electrolyte required to cause coagulation of a colloidal solution. It is inversely proportional to the coagulation power of the electrolyte.

### Step 2: Know the Relationship
Since flocculation value is inversely proportional to coagulation power, we can state:
- Higher coagulation power = Lower flocculation value
- Lower coagulation power = Higher flocculation value

### Step 3: Apply Hardy-Schulze Rule
According to the Hardy-Schulze rule, the coagulation power of an electrolyte increases with the valence of the ion. Therefore, ions with higher charges will have a greater coagulation power.

### Step 4: Analyze the Given Options
Let’s assume the options are:
- A: Pb²⁺
- B: Pb⁴⁺
- C: Na⁺
- D: K⁺

We will evaluate the valence of each ion:
- Pb²⁺ has a valence of 2.
- Pb⁴⁺ has a valence of 4.
- Na⁺ has a valence of 1.
- K⁺ has a valence of 1.

### Step 5: Determine Coagulation Power
From the analysis:
- Pb⁴⁺ has the highest valence (4), thus it has the highest coagulation power.
- Pb²⁺ has a lower coagulation power than Pb⁴⁺.
- Na⁺ and K⁺ have the lowest coagulation power (1).

### Step 6: Conclusion
Since flocculation value is inversely proportional to coagulation power, the ion with the highest coagulation power (Pb⁴⁺) will have the minimum flocculation value.

Thus, the correct answer is **B: Pb⁴⁺**.