The correct sequence of increasing covalent character is represent by

Options

A. LiCl lt NaCl lt `BeCl_2`
B. `BeCl_2 lt NaCl lt LiCl`
C. `NaCl lt LiCl lt BeCl_2`
D. `BeCl_2 lt LiCl lt NaCl`

Explanation

To determine the correct sequence of increasing covalent character among the given molecules, we can follow these steps:

### Step 1: Understand the Concept of Covalent Character
Covalent character refers to the extent to which a bond between two atoms exhibits characteristics of covalent bonding as opposed to ionic bonding. Generally, bonds between atoms of similar electronegativities exhibit more covalent character.

### Step 2: Analyze the Position of Atoms in the Periodic Table
- As we move from left to right across a period in the periodic table, the electronegativity of the elements increases. This leads to an increase in covalent character.
- Conversely, as we move down a group, the ionic character tends to increase due to the larger atomic size and lower electronegativity of the elements.

### Step 3: Compare Elements
- Compare the elements in the question based on their positions in the periodic table.
- For example, consider lithium (Li) and beryllium (Be):
- Beryllium is to the right of lithium, so it has more covalent character than lithium.

- Next, compare lithium (Li) and sodium (Na):
- Sodium is below lithium in the periodic table. As we move down the group, the ionic character increases. Therefore, lithium has more covalent character than sodium.

### Step 4: Continue the Comparison
- Now, compare sodium (Na) and potassium (K):
- Potassium is below sodium in the periodic table, which means potassium will have more ionic character than sodium. Thus, sodium has more covalent character than potassium.

### Step 5: Summarize the Findings
Based on the comparisons:
- Beryllium (Be) > Lithium (Li) > Sodium (Na) > Potassium (K) in terms of increasing covalent character.

### Final Order
The correct sequence of increasing covalent character is:
**Potassium (K) < Sodium (Na) < Lithium (Li) < Beryllium (Be)**