Which of the following is incorect?

Options

A. HydrogengtDeuteriumgtTritium, (%relative abundance)
B. Hydrogen`lt`Deuterium`lt`Tritium,(density/g `L^(-1)`)
C. Hydrogen`lt`deuterium`lt`tritium,(boiling ponit/K)
D. HydreogengtDeuteriumgttritium,(melting point/K)

Answer

To determine which of the given statements about the isotopes of hydrogen is incorrect, we will analyze each option step by step.

### Step 1: Identify the isotopes of hydrogen
Hydrogen has three isotopes:
1. **Protium (¹H)** - Mass number 1
2. **Deuterium (²H)** - Mass number 2
3. **Tritium (³H)** - Mass number 3

### Step 2: Understand isotopes
Isotopes are atoms of the same element that have the same atomic number but different mass numbers. This means they have the same number of protons but a different number of neutrons.

### Step 3: Analyze each option
1. **Option 1: Relative abundance of isotopes**
- Protium is the most abundant isotope, followed by Deuterium, and Tritium is the least abundant due to its radioactivity.
- **Conclusion**: This statement is **correct**.

2. **Option 2: Increasing order of density**
- Density is directly related to mass. Protium has the least mass, followed by Deuterium, and Tritium has the most mass.
- Therefore, the order of increasing density is Protium < Deuterium < Tritium.
- **Conclusion**: This statement is **correct**.

3. **Option 3: Increasing order of boiling point**
- The boiling point increases with mass. Thus, the order should be Protium < Deuterium < Tritium.
- **Conclusion**: This statement is **correct**.

4. **Option 4: Increasing order of melting point**
- Similar to boiling point, the melting point also increases with mass. Therefore, the correct order should be Protium < Deuterium < Tritium.
- If the order given is Protium (¹H) has the maximum melting point, it contradicts the relationship between mass and melting point.
- **Conclusion**: This statement is **incorrect**.

### Final Answer
The incorrect statement is **Option 4**.

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