With increase in temperature of water above `4^@C`, density of water:

Options

A. increases
B. decreases
C. first increases
D. then decreases

Answer

### Step-by-Step Solution:

1. **Understanding the Density of Water at 4°C**:
- At 4 degrees Celsius, water reaches its maximum density. This is a unique property of water, where it behaves differently compared to most substances.

2. **Effect of Temperature Increase**:
- When the temperature of water is increased above 4 degrees Celsius, the kinetic energy of the water molecules increases. This causes the molecules to move apart from each other.

3. **Change in Density**:
- As the molecules move further apart, the volume of water increases while the mass remains the same. Since density is defined as mass divided by volume (Density = Mass/Volume), an increase in volume with constant mass leads to a decrease in density.

4. **Conclusion**:
- Therefore, when the temperature of water is increased above 4 degrees Celsius, the density of water decreases.

### Final Answer:
- The density of water decreases when the temperature is increased above 4°C.

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