The number of moles of solute present in 1000 gm of the solvent is known as:

Options

A. Molarity
B. Molality
C. Normality
D. Mole fraction.

Answer

To solve the question, we need to identify the term that describes the number of moles of solute present in 1000 grams of solvent. Let's break this down step by step.

### Step-by-Step Solution:

1. **Understanding the Question**:
The question asks for a specific term that refers to the number of moles of solute in a given mass of solvent (1000 grams).

2. **Identifying Key Terms**:
- **Molarity (M)**: Defined as the number of moles of solute per liter of solution. This does not relate to the mass of solvent directly.
- **Molality (m)**: Defined as the number of moles of solute per kilogram of solvent. Since 1000 grams is equal to 1 kilogram, this is relevant to our question.
- **Normality (N)**: Defined as the number of equivalents of solute per liter of solution. This is also not related to the mass of solvent directly.
- **Mole Fraction**: Defined as the ratio of the number of moles of solute to the total number of moles of all components in the solution. This does not directly address the mass of solvent.

3. **Analyzing Options**:
- **Molarity**: Not applicable since it involves volume, not mass of solvent.
- **Molality**: This is applicable as it directly relates to the mass of the solvent (in kilograms).
- **Normality**: Not applicable since it involves equivalents and volume.
- **Mole Fraction**: Not applicable as it involves ratios of moles, not mass.

4. **Conclusion**:
Based on the definitions and the analysis of the options, the correct answer is **Molality**. It is defined as the number of moles of solute per kilogram of solvent, which matches the requirement of the question.

### Final Answer:
The number of moles of solute present in 1000 grams of the solvent is known as **Molality**.

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