When electricity is passed through water, then a change V occurs which leads to the formation of two gases W and X. On the other hand, when water is heated strongly, then a change Y takes place leading to the formation of gas Z.
What is the gas X?

Answer

To solve the question, we need to analyze the processes described in the question carefully.

### Step-by-Step Solution:

1. **Understanding the Process of Electrolysis**:
- When electricity is passed through water (H2O), a process called electrolysis occurs. This process involves breaking down water into its constituent elements.

**Hint**: Remember that electrolysis involves using electricity to split compounds into their elements.

2. **Identifying the Gases Produced**:
- During electrolysis of water, two gases are produced: hydrogen (H2) and oxygen (O2).
- Typically, hydrogen is produced at the cathode (negative electrode) and oxygen at the anode (positive electrode).

**Hint**: Recall that water is made of two hydrogen atoms and one oxygen atom (H2O).

3. **Assigning the Gases to W and X**:
- In the question, it states that two gases W and X are formed.
- We can assign W to hydrogen (H2) and X to oxygen (O2).

**Hint**: Think about the common reactions involving water and the products formed.

4. **Understanding the Heating Process**:
- The question also mentions that when water is heated strongly, it changes into water vapor (gas Z). This process is known as vaporization.

**Hint**: Heating water changes its state from liquid to gas, which is a physical change.

5. **Conclusion**:
- Since we have identified that gas X produced during electrolysis is oxygen (O2), we can conclude that the answer to the question is:
- **Gas X is Oxygen (O2)**.

### Final Answer:
Gas X is Oxygen (O2).