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 solve the question regarding the correctness of statements about mole fractions in a solution, we will analyze each statement step by step.

### Step-by-Step Solution:

1. **Understanding Mole Fraction**:
- The mole fraction (x) of a component in a solution is defined as the ratio of the number of moles of that component to the total number of moles of all components in the solution.
- Mathematically, for component A, it can be expressed as:
\[ x_A = \frac{n_A}{n_A + n_B} \]
- Where \( n_A \) is the number of moles of component A and \( n_B \) is the number of moles of component B.

2. **Sum of Mole Fractions**:
- If we consider two components A and B, the mole fractions can be added:
\[ x_A + x_B = \frac{n_A}{n_A + n_B} + \frac{n_B}{n_A + n_B} \]
- Simplifying this gives:
\[ x_A + x_B = \frac{n_A + n_B}{n_A + n_B} = 1 \]
- Therefore, the sum of the mole fractions of all components in a solution is always equal to 1.

3. **Analyzing Each Statement**:
- **Statement 1**: "The sum of the mole fraction of all the components in a solution is always unity."
- This statement is **correct** based on our calculations.

- **Statement 2**: "The mole fraction depends upon temperature."
- This statement is **incorrect**. The mole fraction is a ratio that depends on the number of moles, which is related to mass and does not change with temperature for a given amount of substance.

- **Statement 3**: "Mole fraction is always negative."
- This statement is **incorrect**. Since mole fractions are ratios of moles, they can never be negative; they are always positive values.

- **Statement 4**: "Mole fraction is independent of the content of solute in solution."
- This statement is **incorrect**. The mole fraction is directly related to the amount of solute present in the solution; thus, it cannot be independent of it.

4. **Conclusion**:
- The only correct statement is **Statement 1**: "The sum of the mole fraction of all the components in a solution is always unity."

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