Statement -1: Enthalpy and entropy of any elements substance in the standard states are taken as zero .
Statement-2: At absolute zero , partiles of the perfectly crystalline substance become completely motioness.

Options

A. Statement-1 is True, Statement -2 is True, Statement-2 is a correct explanation for Statement-1.
B. Statement -1 is True ,Starement -2 is True ,Statement-2 is not a correct explanation for Statement-1
C. Statement-1 is True ,Statement-2 is False.
D. Statement-1 is False ,Statement-2 is True.

Answer

To analyze the given statements, we will evaluate each statement separately and determine their truthfulness.

### Step 1: Evaluate Statement 1
**Statement 1:** "Enthalpy and entropy of any elemental substance in the standard states are taken as zero."

- **Enthalpy:** In thermodynamics, the standard enthalpy of formation of an element in its standard state is defined as zero. This is because it is the reference point for measuring the enthalpy of other substances. Therefore, this part of the statement is **true**.

- **Entropy:** The standard entropy of an element in its standard state is not necessarily zero. For example, gases have a certain degree of randomness and thus possess positive entropy values. Therefore, the entropy of an elemental substance in its standard state is not taken as zero. This part of the statement is **false**.

**Conclusion for Statement 1:** The overall statement is **false** because while enthalpy is zero, entropy is not necessarily zero for all elemental substances.

### Step 2: Evaluate Statement 2
**Statement 2:** "At absolute zero, particles of the perfectly crystalline substance become completely motionless."

- According to the third law of thermodynamics, as the temperature approaches absolute zero (0 Kelvin), the entropy of a perfect crystal approaches zero. This implies that the particles in a perfectly crystalline substance have minimal motion at absolute zero. Therefore, this statement is **true**.

**Conclusion for Statement 2:** The statement is **true** because at absolute zero, the motion of particles in a perfect crystal is negligible.

### Final Conclusion
- **Statement 1:** False
- **Statement 2:** True

Thus, the answer is option D: Statement 1 is false and Statement 2 is true.

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