The concentration units. Independent of temperature would be

Options

A. Normality
B. weight volume percent
C. Molality
D. Molarity

Answer

To determine which concentration unit is independent of temperature, we need to analyze the different concentration units and their dependence on volume, which changes with temperature.

### Step-by-Step Solution:

1. **Understanding Concentration Units**:
Concentration can be expressed in various units such as molarity, molality, normality, and weight percent. Each of these has a different relationship with volume and temperature.

2. **Molarity (M)**:
- Definition: Molarity is defined as the number of moles of solute per liter of solution (moles/L).
- Dependence: Since molarity involves volume (liters), and the volume of a solution changes with temperature, molarity is temperature-dependent.

3. **Normality (N)**:
- Definition: Normality is defined as the number of equivalents of solute per liter of solution (equivalents/L).
- Dependence: Similar to molarity, normality also depends on volume. Therefore, it is also temperature-dependent.

4. **Weight Percent (w/v)**:
- Definition: Weight percent is the mass of solute in grams per 100 mL of solution.
- Dependence: Since this unit involves volume (100 mL), it is also temperature-dependent.

5. **Molality (m)**:
- Definition: Molality is defined as the number of moles of solute per kilogram of solvent (moles/kg).
- Dependence: Molality does not involve volume; it is based on the mass of the solvent. Therefore, it remains constant regardless of temperature changes.

6. **Conclusion**:
- Among the concentration units discussed, **molality** is the only unit that is independent of temperature because it does not involve volume, which changes with temperature.

### Final Answer:
The concentration unit that is independent of temperature is **molality**.

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