The diagonal relationship exists is between

Options

A. Li and Mg
B. Be and Al
C. Be and Na
D. B and Si

Answer

To determine the diagonal relationship that exists between the given elements, we need to analyze the options provided. The diagonal relationship typically occurs between certain pairs of elements in the s-block and p-block of the periodic table due to similarities in their properties.

### Step-by-Step Solution:

1. **Understanding Diagonal Relationship**:
The diagonal relationship in the periodic table refers to the similarities in properties between elements that are diagonally positioned from each other. This is often observed between elements of group 1 and group 2, and between certain p-block elements.

2. **Analyzing the Options**:
- **Option 1: Lithium (Li) and Magnesium (Mg)**:
- Lithium is in group 1, and Magnesium is in group 2. They are diagonally positioned in the periodic table. This pair exhibits similarities in properties such as ionic size and reactivity.

- **Option 2: Beryllium (Be) and Aluminium (Al)**:
- Beryllium is in group 2, and Aluminium is in group 13. They are also diagonally positioned. Beryllium and Aluminium share some similar properties, such as their ability to form covalent compounds.

- **Option 3: Beryllium (Be) and Sodium (Na)**:
- Beryllium is in group 2, and Sodium is in group 1. However, they do not exhibit a diagonal relationship as their properties differ significantly.

- **Option 4: Boron (B) and Silicon (Si)**:
- Boron is in group 13, and Silicon is in group 14. They are also diagonally positioned, and they share some similarities in properties, such as their ability to form covalent bonds.

3. **Identifying Correct Options**:
- From the analysis, we find that:
- **Option 1 (Li and Mg)**: Correct
- **Option 2 (Be and Al)**: Correct
- **Option 3 (Be and Na)**: Incorrect
- **Option 4 (B and Si)**: Correct

4. **Conclusion**:
The diagonal relationships exist between:
- Lithium and Magnesium (Option 1)
- Beryllium and Aluminium (Option 2)
- Boron and Silicon (Option 4)

Thus, the answer to the question is that diagonal relationships exist between **Option 1, Option 2, and Option 4**.