In a pair of immiscible liquid, a common solute dissolves in both and the equilibrium is reached. Then, the concentration of the solute in upper layer is

Options

A. in fixed ratio with that in the lower layer
B. same as the lower layer
C. lower than the lower layer
D. higher than the lower layer

Explanation

To solve the problem regarding the concentration of a common solute in a pair of immiscible liquids at equilibrium, we can follow these steps:

### Step 1: Understand the System
We have two immiscible liquids, Liquid A (upper layer) and Liquid B (lower layer). A common solute (let's denote it as X) is dissolved in both liquids.

**Hint:** Identify the two layers and the solute involved in the system.

### Step 2: Define Concentrations
At equilibrium, let the concentration of the solute X in Liquid A be denoted as [X]A and in Liquid B as [X]B.

**Hint:** Use symbols to represent the concentrations for clarity.

### Step 3: Apply the Partition Law
According to the partition law (also known as the distribution law), the ratio of the concentrations of the solute in the two immiscible layers is constant. This can be expressed mathematically as:

\[ \frac{[X]A}{[X]B} = K_D \]

where \( K_D \) is the distribution constant for the solute between the two liquids.

**Hint:** Remember that the partition law relates the concentrations of the solute in both layers.

### Step 4: Rearranging the Equation
From the equation above, we can rearrange it to find the concentration of the solute in the upper layer (Liquid A):

\[ [X]A = K_D \cdot [X]B \]

This equation shows that the concentration of the solute in the upper layer is directly proportional to the concentration in the lower layer, scaled by the distribution constant.

**Hint:** Rearranging equations can help isolate the variable of interest.

### Step 5: Conclusion
Thus, the concentration of the solute in the upper layer (Liquid A) can be expressed in terms of the concentration in the lower layer (Liquid B) and the distribution constant.

**Final Answer:** The concentration of the solute in the upper layer is given by the equation \( [X]A = K_D \cdot [X]B \).