The diagonal relationship exists in between

Options

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

Answer

To determine the pairs of elements that exhibit a diagonal relationship, we need to analyze the elements in the second and third periods of the periodic table. The diagonal relationship typically exists between certain pairs of elements from these periods due to their similar properties.

### Step-by-Step Solution:

1. **Identify the Elements**:
- The elements mentioned in the question are:
- Lithium (Li) and Sodium (Na)
- Beryllium (Be) and Magnesium (Mg)
- Boron (B) and Aluminium (Al)
- Beryllium (Be) and Sodium (Na)
- Boron (B) and Silicon (Si)

2. **Locate the Elements in the Periodic Table**:
- Lithium (Li) is in Group 1 and Period 2.
- Sodium (Na) is in Group 1 and Period 3.
- Beryllium (Be) is in Group 2 and Period 2.
- Magnesium (Mg) is in Group 2 and Period 3.
- Boron (B) is in Group 13 and Period 2.
- Aluminium (Al) is in Group 13 and Period 3.
- Silicon (Si) is in Group 14 and Period 3.

3. **Analyze the Diagonal Relationships**:
- **Li and Mg**: Lithium (Group 1) and Magnesium (Group 2) show similarities in properties such as reactivity and ionic character.
- **Be and Al**: Beryllium (Group 2) and Aluminium (Group 13) also exhibit similar chemical properties, such as amphoteric behavior.
- **B and Si**: Boron (Group 13) and Silicon (Group 14) share some properties like being metalloids and forming covalent compounds.
- **Be and Na**: Beryllium (Group 2) and Sodium (Group 1) do not show a diagonal relationship as they belong to different groups with distinct properties.
- **B and Al**: This pair does show a diagonal relationship as mentioned.

4. **Conclusion**:
- The diagonal relationships exist between:
- Lithium and Magnesium
- Beryllium and Aluminium
- Boron and Silicon
- The pair that does not exhibit a diagonal relationship is Beryllium and Sodium.

### Final Answer:
The diagonal relationship exists between Lithium and Magnesium, Beryllium and Aluminium, and Boron and Silicon. However, Beryllium and Sodium do not show a diagonal relationship.