Assertion. At 298 K and 1 atm pressure, solids do not have any entropy but liquids and gases have definite values of entropy.
Reason . At 298 K and 1 atm pressure, particle in a solid are fixed and do not have translatory, rotatory or vibraory motion whereas in liquids and gases, molecules have all the three types of motion.

Options

A. If both A and R are true,andR is the true explanation of A.
B. If both A and R are true,but R is not the true explanation of A.
C. If A is true, but R is false
D. If both A and R are false.

Answer

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

### Step-by-step Solution:

1. **Understanding the Assertion:**
- The assertion states that at 298 K and 1 atm pressure, solids do not have any entropy, while liquids and gases have definite values of entropy.
- This statement is **incorrect**. While it is true that solids have lower entropy compared to liquids and gases, they do possess some entropy. The entropy of a solid is not zero at room temperature (298 K); it is simply lower than that of liquids and gases.

2. **Understanding the Reason:**
- The reason provided states that at 298 K and 1 atm pressure, particles in a solid are fixed and do not have translatory, rotatory, or vibratory motion, whereas in liquids and gases, molecules have all three types of motion.
- This statement is also **incorrect**. While it is true that particles in a solid are more fixed compared to those in liquids and gases, they do exhibit vibrational motion. Therefore, solids do have some degree of motion, which contributes to their entropy.

3. **Conclusion:**
- Since both the assertion and the reason are incorrect, the correct answer to the question is that both the assertion and the reason are false.

### Final Answer:
Both the assertion and the reason are false.