The expansion of a gas into an evacuated space takes place non-spontaneously.
A process in which all steps cannot be retraced by themselves is called a spontaneous process.

Options

A. If both the statements are TRUE and STATEMENT-2 is the correct explanation of STATEMENT-18
B. If both the statements are TRUE but STATEMENT-2 is NOT the correct explanation of STATEMENT-18
C. If STATEMENT-1 is TRUE and STATEMENT-2 is FALSE
D. If STATEMENT-1 is FALSE and STATEMENT-2 is TRUE

Answer

To solve the question, we need to analyze the two statements provided:

1. **Statement 1**: "The expansion of a gas into an evacuated space takes place non-spontaneously."
2. **Statement 2**: "A process in which all steps cannot be retraced by themselves is called a spontaneous process."

### Step-by-Step Solution:

**Step 1: Analyze Statement 1**
- The expansion of a gas into an evacuated space refers to a gas moving from a region of higher pressure to a region of lower pressure (the evacuated space).
- According to the principles of thermodynamics, this process occurs spontaneously because it leads to an increase in entropy (disorder) of the system.
- Therefore, Statement 1 is **false**.

**Step 2: Analyze Statement 2**
- The second statement describes a process where all steps cannot be retraced by themselves. This is a characteristic of irreversible processes.
- Spontaneous processes are typically irreversible; once they occur, they cannot return to their original state without external work being done.
- Thus, Statement 2 is **true**.

### Conclusion:
- Statement 1 is false, and Statement 2 is true. Therefore, the overall answer is that the first statement is incorrect while the second statement is correct.

### Final Answer:
- Statement 1: False
- Statement 2: True

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