The conductivity test is positive for

Options

A. O/W
B. W/O
C. Both (1) & (2)
D. None of these

Answer

To determine which type of emulsion has a positive conductivity test, we need to analyze the properties of emulsions and their components. Here’s a step-by-step solution:

### Step 1: Understand Emulsions
Emulsions are colloidal systems where both the dispersed phase and the dispersion medium are liquids. They can be categorized into two types:
- Oil in Water (O/W)
- Water in Oil (W/O)

**Hint:** Remember that emulsions consist of two liquids, and their classification depends on which liquid is dispersed in the other.

### Step 2: Identify the Components
In an Oil in Water (O/W) emulsion:
- Dispersed Phase: Oil
- Dispersion Medium: Water

In a Water in Oil (W/O) emulsion:
- Dispersed Phase: Water
- Dispersion Medium: Oil

**Hint:** Identify which component acts as the continuous phase (dispersion medium) in each type of emulsion.

### Step 3: Conductivity of the Components
Water is known to be a good conductor of electricity due to its ability to dissociate into ions. On the other hand, oil is a poor conductor of electricity.

**Hint:** Recall that the conductivity of a solution depends on the presence of ions, which are abundant in water but not in oil.

### Step 4: Analyze the Conductivity Test
For the O/W emulsion:
- Since water is the dispersion medium, adding an electrolyte (like NaCl) will increase the conductivity significantly because the water can conduct electricity.

For the W/O emulsion:
- The dispersion medium is oil, which does not conduct electricity well. Therefore, adding an electrolyte will not significantly increase conductivity.

**Hint:** Consider how the presence of a conductive medium (water) versus a non-conductive medium (oil) affects the overall conductivity of the emulsion.

### Step 5: Conclusion
Based on the analysis, the conductivity test will be positive for the Oil in Water (O/W) emulsion because it contains water as the continuous phase, which is a good conductor of electricity.

Thus, the correct answer is:
**Oil in Water (O/W) emulsion.**

### Final Answer:
The conductivity test is positive for **Oil in Water (O/W) emulsion**.