`5g` each of two solutes `X` and Y ( mol. `wt` of `X gt Y)` are dissolved in `100g` each of same solvent.

Options

A. Solution of Y shows greater elevation of boiling point
B. Solution of X shows greater elevation of boiling point
C. Both solutinos of X and Y boils at the same temperature
D. Solution of X freezes after freezing of solution Y

Explanation

To solve the problem step by step, we will analyze the relationship between the solutes X and Y, their molar masses, and how they affect the boiling point elevation of the solution.

### Step 1: Understand the Given Information
We have two solutes, X and Y, each weighing 5 grams, dissolved in 100 grams of the same solvent. We know that the molecular weight of solute X is greater than that of solute Y.

### Step 2: Recall the Formula for Boiling Point Elevation
The boiling point elevation (\( \Delta T_b \)) can be calculated using the formula:
\[ \Delta T_b = K_b \cdot m \]
where:
- \( K_b \) is the ebullioscopic constant of the solvent (which is the same for both solutions since they are dissolved in the same solvent),
- \( m \) is the molality of the solution.

### Step 3: Calculate Molality
Molality (\( m \)) is defined as the number of moles of solute per kilogram of solvent:
\[ m = \frac{\text{moles of solute}}{\text{mass of solvent in kg}} \]
Given that the mass of the solvent is 100 grams (or 0.1 kg), we can express molality as:
\[ m = \frac{\text{moles of solute}}{0.1} \]

### Step 4: Calculate Moles of Solute
The number of moles of solute can be calculated using the formula:
\[ \text{moles of solute} = \frac{\text{mass of solute}}{\text{molecular weight of solute}} \]
For solute X:
\[ \text{moles of X} = \frac{5 \, \text{g}}{M_X} \quad \text{(where \( M_X \) is the molecular weight of X)} \]
For solute Y:
\[ \text{moles of Y} = \frac{5 \, \text{g}}{M_Y} \quad \text{(where \( M_Y \) is the molecular weight of Y)} \]

### Step 5: Compare Moles of Solute
Since \( M_X > M_Y \), it follows that:
\[ \frac{5}{M_X} < \frac{5}{M_Y} \]
This means that the number of moles of solute Y is greater than that of solute X:
\[ \text{moles of Y} > \text{moles of X} \]

### Step 6: Determine the Effect on Molality
Since the molality depends on the number of moles of solute, we can conclude:
\[ m_Y > m_X \]
Thus, the molality of the solution containing solute Y is greater than that of the solution containing solute X.

### Step 7: Conclusion on Boiling Point Elevation
Since the boiling point elevation (\( \Delta T_b \)) is directly proportional to the molality, we have:
\[ \Delta T_{bY} > \Delta T_{bX} \]
This means that the solution of Y shows a greater elevation in boiling point compared to the solution of X.

### Final Answer
The solution of Y shows a greater elevation in boiling point than that of X.