Assertion: The sum of mol fractions of all the components of a solution is unity.
Reason: Mole fraction is temperature dependent mode of concentrations.

Answer

To solve the assertion-reason question, we need to analyze both the assertion and the reason provided.

### Step 1: Analyze the Assertion
The assertion states: "The sum of mole fractions of all the components of a solution is unity."

- **Definition of 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.

- **Mathematical Representation**:
- Let’s consider two components A and B in a solution.
- If \( n_A \) is the number of moles of A and \( n_B \) is the number of moles of B, then:
- Mole fraction of A, \( X_A = \frac{n_A}{n_A + n_B} \)
- Mole fraction of B, \( X_B = \frac{n_B}{n_A + n_B} \)

- **Sum of Mole Fractions**:
\[ X_A + X_B = \frac{n_A}{n_A + n_B} + \frac{n_B}{n_A + n_B} = \frac{n_A + n_B}{n_A + n_B} = 1 \]

Thus, the assertion is **true**.

### Step 2: Analyze the Reason
The reason states: "Mole fraction is a temperature-dependent mode of concentration."

- **Understanding Mole Fraction**: Mole fraction is calculated based on the number of moles of each component in the solution. It does not depend on temperature or pressure; it is solely a function of the amount of substance present.

- **Conclusion**: Since mole fraction does not change with temperature, the reason is **false**.

### Final Conclusion
- The assertion is true: The sum of mole fractions of all components of a solution is indeed unity.
- The reason is false: Mole fraction is not temperature-dependent.

### Answer:
- Assertion: True
- Reason: False