Which of the following statements is correct?

Options

A. Density of water remain unchanged when something dissolves In water completely
B. Petrol and water mixes completely and they are difficult to separate
C. Dissolution process Is enhanced when sugar Is stirred while dissolving In water
D. If all and water is vigorously shaken both will mix together completely

Answer

To determine which of the statements is correct, let's analyze each one step-by-step:

1. **Statement 1: The density of water remains unchanged when something is dissolved in water completely.**
- When a substance is dissolved in water, the overall mass of the solution increases while the volume may also change, leading to a change in density. Therefore, this statement is **incorrect**.

2. **Statement 2: Petrol and water mix completely and are difficult to separate.**
- Petrol (or gasoline) and water do not mix completely; they are immiscible liquids. When combined, they form two separate layers and can be easily separated. Thus, this statement is also **incorrect**.

3. **Statement 3: The dissolution process enhances while dissolving in water.**
- When a solute like sugar is added to water, stirring helps to disperse the solute evenly throughout the solvent. This process indeed enhances the dissolution as the solute particles move between the water molecules. Therefore, this statement is **correct**.

4. **Statement 4: If oil and water are vigorously shaken, both will mix together completely.**
- Similar to petrol and water, oil and water do not mix completely, even if shaken vigorously. They will eventually separate into two distinct layers. Hence, this statement is **incorrect**.

Based on the analysis, the correct statement is **Statement 3**.

### Final Answer:
The correct statement is: **The dissolution process enhances while dissolving in water.**