Assertion (A): Molarity of a solution changes with temperature.
Reason (R): Molarity is dependent on volume of solution.

Options

A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true but R is NOT the correct explanation of A
C. A is true but R is false
D. A is false and R is True

Explanation

To solve the assertion and reason question, we will analyze both the assertion (A) and the reason (R) step by step.

### Step 1: Understand the Assertion
**Assertion (A): Molarity of a solution changes with temperature.**

- Molarity (M) is defined as the number of moles of solute divided by the volume of the solution in liters.
- Mathematically, it can be expressed as:
\[ M = \frac{n}{V} \]
where \( n \) is the number of moles of solute and \( V \) is the volume of the solution.

### Step 2: Analyze the Effect of Temperature on Volume
- When the temperature of a solution increases, the kinetic energy of the particles also increases.
- As the temperature rises, the particles in the solution move more vigorously and tend to occupy more space, which leads to an increase in the volume of the solution.

### Step 3: Relate Volume Change to Molarity
- Since molarity is inversely related to volume (as volume increases, molarity decreases if the number of moles of solute remains constant), an increase in temperature (which causes an increase in volume) will lead to a decrease in molarity.
- Therefore, the assertion that molarity changes with temperature is true.

### Step 4: Understand the Reason
**Reason (R): Molarity is dependent on volume of solution.**

- The formula for molarity clearly shows that molarity is calculated using the volume of the solution.
- Hence, if the volume changes, the molarity will also change, confirming that molarity is indeed dependent on the volume of the solution.

### Step 5: Conclusion
- Both the assertion (A) and the reason (R) are true.
- The reason provided (R) correctly explains the assertion (A) because molarity's dependence on volume directly ties to its dependence on temperature.

### Final Answer:
Both assertion and reason are true, and the reason is the correct explanation for the assertion.