Which of the following statement about transuranic elements is incorrect?

Options

A. These are all synthetic elements
B. These are elements of atomic number 93 and beyond
C. Elements from 92 to lawrencium are called actinides
D. These are part of fourth transition series

Answer

To determine which statement about transuranic elements is incorrect, we need to analyze each option provided. Transuranic elements are defined as chemical elements with atomic numbers greater than 92 (the atomic number of uranium). Here’s a step-by-step breakdown of the options:

### Step 1: Understand Transuranic Elements
- **Definition**: Transuranic elements are those with atomic numbers greater than 92.
- **Characteristics**: All transuranic elements are unstable and decay radioactively.

### Step 2: Evaluate Each Option

1. **Option 1: These are all synthetic.**
- **Analysis**: All elements heavier than plutonium (atomic number 94) are indeed synthetic and created in laboratories or nuclear reactors. This statement is correct.

2. **Option 2: These are elements of atomic number 93 and beyond.**
- **Analysis**: This statement is also correct because transuranic elements start from atomic number 93 (Neptunium) and go beyond.

3. **Option 3: Elements from 92 to Lawrencium are actinides.**
- **Analysis**: This statement is incorrect. The actinide series includes elements from atomic number 89 (Actinium) to 103 (Lawrencium). Therefore, while uranium (atomic number 92) is not classified as an actinide, the statement incorrectly includes it in the actinide series.

4. **Option 4: These are part of the fourth transition series.**
- **Analysis**: This statement is correct. The fourth transition series includes elements from Rutherfordium (Rf, atomic number 104) to Copernicium (Cn, atomic number 112), which are indeed part of the transition metals.

### Conclusion
- The incorrect statement is **Option 3**, which inaccurately claims that elements from 92 to Lawrencium are actinides.

### Final Answer
**Option 3 is the incorrect statement about transuranic elements.**

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