Question

The repulsive interaction between different types of electron pairs increases in the order of

• A. bond pair - bond pair \(<\) lone pair - bond pair \(<\) lone pair - lone pair
• B. lone pair - lone pair \(<\) lone pair - bond pair \(<\) bond pair - bond pair
• C. lone pair - bond pair \(<\) lone pair - lone pair \(<\) bond pair - bond pair
• D. lone pair - lone pair \(<\) bond pair - bond pair \(<\) lone pair - bond pair

Hint:

In VSEPR theory, lone pairs always exert stronger repulsion than bond pairs because lone pair electrons are localized closer to the central atom.

Answer 1

The Correct Option is A

Step 1: Recall VSEPR theory.
According to Valence Shell Electron Pair Repulsion (VSEPR) theory, electron pairs surrounding the central atom repel one another and arrange themselves to minimize repulsion.

Step 2: Understand bond pairs and lone pairs.
Bond pairs are shared between two atoms and occupy less space around the central atom. Lone pairs are localized on a single atom and occupy more space because their electron density is concentrated closer to the nucleus.

Step 3: Compare bond pair - bond pair repulsion.
Since bonding electrons are shared between atoms, the repulsion between two bond pairs is the weakest among the three types of interactions.

Step 4: Compare lone pair - bond pair repulsion.
A lone pair occupies more space than a bond pair, so the repulsion between a lone pair and a bond pair is stronger than bond pair - bond pair repulsion.

Step 5: Compare lone pair - lone pair repulsion.
Two lone pairs repel each other most strongly because both have highly concentrated electron density around the central atom.

Step 6: Arrange the interactions in increasing order.
Therefore, the increasing order of repulsive interactions is
\[ \text{bond pair - bond pair} < \text{lone pair - bond pair} < \text{lone pair - lone pair} \]

Step 7: Final conclusion.
Hence, the correct order is
\[ \boxed{\text{bond pair - bond pair} < \text{lone pair - bond pair} < \text{lone pair - lone pair}} \]
Therefore, the correct answer is option (A).