Which of the following statements are correct?
I. Yellow flames are ideal for heating.
II. The substances which vaporise during burning give flames.
III. Luminous zone contains unburnt carbon particles.
IV. The non-luminous zone has the highest temperature.

Options

A. I, II and III only
B. II and IV only
C. II, III and IV only
D. I, III and IV only

Explanation

To determine which of the statements are correct, let's analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement I: Yellow flames are ideal for heating.**
- **Analysis:** Yellow flames, such as those produced by a candle, are not ideal for heating because they indicate incomplete combustion. The ideal flame for heating is the blue flame, which indicates complete combustion and higher efficiency.
- **Conclusion:** This statement is **incorrect**.

2. **Statement II: The substances which vaporize during burning give flames.**
- **Analysis:** Flames are produced when substances vaporize and then combust. For example, when a candle burns, the wax vaporizes and then ignites, creating a flame.
- **Conclusion:** This statement is **correct**.

3. **Statement III: Luminous zone contains unburnt carbon particles.**
- **Analysis:** The luminous zone of a flame is the bright, yellow part that indicates incomplete combustion. This zone contains unburnt carbon particles due to insufficient oxygen for complete combustion.
- **Conclusion:** This statement is **correct**.

4. **Statement IV: The non-luminous zone has the highest temperature.**
- **Analysis:** The non-luminous zone, which is the blue part of the flame, is where complete combustion occurs and has a sufficient supply of oxygen. This zone indeed has the highest temperature compared to the luminous zone.
- **Conclusion:** This statement is **correct**.

### Final Summary of Statements:
- Statement I: Incorrect
- Statement II: Correct
- Statement III: Correct
- Statement IV: Correct

### Correct Statements:
The correct statements are II, III, and IV.

---