The correct sequence of increasing covalent character is represented by:

(A) BeCl2 < NaCl < LiCl

(B) NaCl < LiCl < BeCl2

(C) BeCl2 < LiCl < NaCl

(D) LiCl < NaCl < BeCl2

To determine the correct sequence of increasing covalent character among the compounds BeCl2, NaCl, and LiCl, we need to consider the nature of the bonds formed in these compounds and the factors that influence covalent character.

Understanding Ionic vs. Covalent Character

In general, ionic compounds consist of a metal and a non-metal, where the metal donates electrons to the non-metal, resulting in the formation of ions. Covalent compounds, on the other hand, involve the sharing of electrons between atoms. The degree of covalent character in a bond can be influenced by several factors, including:

• Electronegativity: The difference in electronegativity between the two atoms can indicate how ionic or covalent the bond is. A larger difference typically results in a more ionic bond.
• Polarizability: Smaller cations can polarize the electron cloud of anions more effectively, leading to increased covalent character.
• Charge Density: Higher charge density on the cation can lead to greater covalent character due to stronger interactions with the anion.

Analyzing the Compounds

Now, let’s analyze the three compounds:

• BeCl2: Beryllium has a high charge density due to its small size and +2 charge. This allows it to polarize the chloride ions significantly, giving BeCl2 a considerable covalent character despite being an ionic compound.
• LiCl: Lithium, while also a small cation, has a +1 charge, which results in less polarizing power compared to Be2+. Thus, LiCl has more ionic character than BeCl2 but still exhibits some covalent characteristics.
• NaCl: Sodium is larger than lithium and has a +1 charge as well. However, Na+ is less polarizing than Li+, leading to a more pronounced ionic character in NaCl compared to both BeCl2 and LiCl.

Establishing the Sequence

Based on the analysis above, we can rank the compounds in terms of increasing covalent character:

• NaCl has the least covalent character due to its larger cation and more ionic nature.
• LiCl has more covalent character than NaCl because of the smaller size of Li+, which can polarize the chloride ions more effectively.
• BeCl2 has the highest covalent character among the three due to the high charge density of Be2+, which leads to significant polarization of the chloride ions.

Final Ranking

Thus, the correct sequence of increasing covalent character is:

NaCl < LiCl < BeCl2

Therefore, the answer is (B) NaCl < LiCl < BeCl2.