Group 13 Elements

Step 1: Understand the behavior of anhydrous AlCl .
Anhydrous aluminum chloride (AlCl ) is highly reactive and fume in moist air. It undergoes hydrolysis, where it reacts with water vapor in the air to form aluminum hydroxide and hydrochloric acid.

Step 2: Analyze the reactions.
- Oxidation: This involves the loss of electrons, which is not the case for anhydrous AlCl in air.
- Hydrolysis: This is the correct reaction, where AlCl reacts with water vapor to form Al(OH) and HCl.
- Reduction: This involves the gain of electrons, but it is not the reaction for AlCl .
- Hydrogenation: This is the addition of hydrogen, which does not apply to AlCl .

Step 3: Conclusion.
The correct answer is (2), hydrolysis.

Step 1: Understanding the Concept:
In Bessemer converter, copper pyrites (CuFeS ) is roasted to form Cu S and FeO. FeO is removed as slag. Remaining Cu S is then converted to Cu.
Step 2: Detailed Explanation:
Final step (autoreduction): Cu S + 2Cu O 6Cu + SO .
Here, Cu O is produced by partial oxidation of Cu S. The reaction is self-sustaining.
Step 3: Final Answer:
Thus, correct reaction is Cu S + 2Cu O 6Cu + SO .

Step 1: Understanding the Concept:
Lewis acidity depends on both inductive effect and back-donation of lone pairs.

Step 2: Detailed Explanation:
BF is the weakest Lewis acid because F donates its lone pairs strongly to B (p -p back-bonding), reducing electron deficiency. As we go down the group, back-bonding decreases, so Lewis acidity increases. Order: BI >BBr >BCl >BF .

Step 3: Final Answer:

Concept: Solubility of ionic compounds depends on the balance between lattice energy and hydration energy. For alkaline earth metal fluorides, lattice energy dominates the trend.

Step 1: Identify the trend. Down the group (Mg → Ba):
• Cation size increases
• Lattice energy decreases (but slowly)
• Hydration energy decreases significantly (due to larger cation size)

Step 2: Compare lattice energy vs hydration energy. For fluorides, the decrease in hydration energy down the group is more rapid than the decrease in lattice energy. As a result, solubility decreases down the group: MgF is relatively more soluble, while BaF is the least soluble.

Step 3: Conclusion. Option (A) gives the correct decreasing order.

Concept: Hydroboration reaction:

Step 1: Reaction type.
Diborane adds across double bonds.

Step 2: Product.
Forms trialkyl borane:

Concept: Diborane ( ) contains:
•Terminal B–H bonds → bonds
•Bridge B–H–B bonds → bonds

Step 1: Count bonds
•Terminal bonds = 4 (2c-2e)
•Bridge bonds = 2 (3c-2e)

Step 2: Total bonds Conclusion