Give two examples of an irreversible process.

Explanation

**Step-by-Step Text Solution:**

1. **Understanding Irreversible Processes**: An irreversible process is a process that cannot be reversed to restore the system and its surroundings to their original states. These processes increase the entropy of the universe.

2. **Example 1: Free Expansion of Gas**:
- In free expansion, a gas expands into a vacuum without doing any work and without heat exchange with the surroundings.
- Once the gas has expanded, it cannot spontaneously compress back into its original volume without external work being done.

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