Find the total number of elements which have higher ionisation energy than their both adjacent elements (either in a period or in a group in the long from of periodic table).
`Be, B, N, P, Ga, Mg`

Answer

To find the total number of elements which have higher ionization energy than their both adjacent elements (either in a period or in a group), we will analyze the given elements: Be (Beryllium), B (Boron), N (Nitrogen), P (Phosphorus), Ga (Gallium), and Mg (Magnesium).

### Step-by-Step Solution:

1. **Identify the Elements and Their Positions**:
- The elements given are: Be, B, N, P, Ga, and Mg.
- We will analyze their positions in the periodic table to determine their adjacent elements.

2. **Check Ionization Energies**:
- **Beryllium (Be)**:
- Adjacent elements: Lithium (Li) and Boron (B).
- Ionization energy of Be > Ionization energy of B and Li.
- **Boron (B)**:
- Adjacent elements: Be and Carbon (C).
- Ionization energy of B < Ionization energy of Be and C. (Not considered)
- **Nitrogen (N)**:
- Adjacent elements: Boron (B) and Oxygen (O).
- Ionization energy of N > Ionization energy of B and O.
- **Phosphorus (P)**:
- Adjacent elements: Silicon (Si) and Sulfur (S).
- Ionization energy of P > Ionization energy of Si and S.
- **Gallium (Ga)**:
- Adjacent elements: Aluminum (Al) and Indium (In).
- Ionization energy of Ga > Ionization energy of Al and In.
- **Magnesium (Mg)**:
- Adjacent elements: Sodium (Na) and Aluminum (Al).
- Ionization energy of Mg > Ionization energy of Na and Al.

3. **Count the Elements with Higher Ionization Energy**:
- From the analysis:
- Be has higher ionization energy than both adjacent elements.
- N has higher ionization energy than both adjacent elements.
- P has higher ionization energy than both adjacent elements.
- Ga has higher ionization energy than both adjacent elements.
- Mg has higher ionization energy than both adjacent elements.
- B does not qualify as it has lower ionization energy than its adjacent elements.

4. **Total Count**:
- The qualifying elements are: Be, N, P, Ga, and Mg.
- Total number of elements = 5.

### Final Answer:
The total number of elements which have higher ionization energy than their both adjacent elements is **5**.