Which of the following is correct?

Options

A. The sum of mole fractions of all the components in a solution is always unity
B. Mole fraction depends upon temperature
C. Mole fraction is always negative
D. Mole fraction is independent of content of solute in solution.

Answer

To determine which of the given statements about mole fractions is correct, we will analyze each option step by step.

### Step 1: Analyze the First Statement
**Statement:** The sum of mole fractions of all the components in a solution is always unity.

**Explanation:**
- The mole fraction of a component is defined as the number of moles of that component divided by the total number of moles of all components in the solution.
- If we have components A, B, and C, the mole fractions can be expressed as:
- Mole fraction of A (X_A) = moles of A / (moles of A + moles of B + moles of C)
- Mole fraction of B (X_B) = moles of B / (moles of A + moles of B + moles of C)
- Mole fraction of C (X_C) = moles of C / (moles of A + moles of B + moles of C)
- Adding these fractions gives:
\[ X_A + X_B + X_C = \frac{moles of A + moles of B + moles of C}{moles of A + moles of B + moles of C} = 1 \]
- Therefore, this statement is **correct**.

### Step 2: Analyze the Second Statement
**Statement:** Mole fraction depends upon temperature.

**Explanation:**
- The mole fraction is calculated based on the number of moles of each component, which is derived from mass and molar mass.
- The mass of a substance does not change with temperature, and thus the mole fraction does not depend on temperature.
- Therefore, this statement is **incorrect**.

### Step 3: Analyze the Third Statement
**Statement:** Mole fraction is always negative.

**Explanation:**
- The mole fraction is defined as the ratio of the number of moles of a component to the total number of moles in the solution.
- Since the number of moles cannot be negative, the mole fraction cannot be negative either.
- Therefore, this statement is **incorrect**.

### Step 4: Analyze the Fourth Statement
**Statement:** Mole fraction is independent of the content of solute in solution.

**Explanation:**
- The mole fraction of a component is directly calculated from the number of moles of that component relative to the total number of moles, which includes the solute.
- Therefore, the mole fraction is dependent on the amount of solute present in the solution.
- Thus, this statement is **incorrect**.

### Conclusion
After analyzing all the statements, we find that:
- The first statement is correct: **The sum of mole fractions of all the components in a solution is always unity.**

### Final Answer
The correct option is **1**.

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