Question

In which of the following pairs first compound has more covalent nature than second compound? (a) \( \text{SnCl}_2, \text{SnCl}_4 \) (b) \( \text{PbCl}_4, \text{PbCl}_2 \) (c) \( \text{UF}_6, \text{UF}_4 \)

• A. Only (a) and (b)
• B. Only (b) and (c)
• C. Only (a) and (c)
• D. Only (c)

Hint:

Covalent character increases with lower oxidation states and smaller ionic radii. Higher oxidation states tend to favor ionic character.

Answer 1

The Correct Option is B

Step 1: Understand the relationship between covalent and ionic bonding.
Covalent bonding generally increases as the size of the central atom decreases and its electronegativity increases. Compounds where the central atom has a low oxidation state typically exhibit more covalent character compared to those with high oxidation states, which tend to exhibit more ionic character.
Step 2: Analyze pair (a) \( \text{SnCl}_2, \text{SnCl}_4 \).
- In \( \text{SnCl}_2 \), the oxidation state of Sn is +2, while in \( \text{SnCl}_4 \), the oxidation state of Sn is +4. - Higher oxidation states (like +4) generally lead to more ionic character, and lower oxidation states (like +2) lead to more covalent character. Thus, \( \text{SnCl}_2 \) has more covalent nature than \( \text{SnCl}_4 \), so statement (a) is correct.
Step 3: Analyze pair (b) \( \text{PbCl}_4, \text{PbCl}_2 \).
- In \( \text{PbCl}_4 \), Pb is in the +4 oxidation state, and in \( \text{PbCl}_2 \), Pb is in the +2 oxidation state. - \( \text{PbCl}_2 \), with Pb in the +2 oxidation state, has more covalent character than \( \text{PbCl}_4 \), which has more ionic character due to the higher oxidation state. Thus, \( \text{PbCl}_2 \) has more covalent nature than \( \text{PbCl}_4 \), so statement (b) is correct.
Step 4: Analyze pair (c) \( \text{UF}_6, \text{UF}_4 \).
- In \( \text{UF}_6 \), U is in the +6 oxidation state, and in \( \text{UF}_4 \), U is in the +4 oxidation state. - As discussed, lower oxidation states tend to favor covalent bonding, so \( \text{UF}_4 \) has more covalent character than \( \text{UF}_6 \), so statement (c) is correct.
Step 5: Conclusion.
Thus, the correct answer is (2) Only (b) and (c).