Question

A Lewis acid 'X' reacts with LiAlH$_4$ in either medium to give a highly toxic gas, 'Y'. 'Y' when heated with NH$_3$ gives a compound known as inorganic benzene. 'Y' burns in oxygen and gives H$_2$O and 'Z'. 'Z' is:

• A. Basic oxide
• B. Acidic oxide
• C. Amphoteric acid
• D. Neutral oxide

Hint:

When a compound burns in oxygen and forms an acidic product, it is likely to be an acidic oxide. Remember, acidic oxides form acidic solutions when dissolved in water.

Answer 1

The Correct Option is B

Given that 'X' reacts with LiAlH$_4$ to give a toxic gas 'Y', and 'Y' when heated with NH$_3$ gives inorganic benzene, we can identify 'Y' as borane (BH$_3$) or its derivatives, which are known to form inorganic benzene.
- Borane (BH$_3$) is a highly reactive compound and burns in oxygen to form water (H$_2$O).
- Upon combustion, borane (BH$_3$) forms boron oxides, which are acidic in nature.
Therefore, 'Z' is an acidic oxide, as it reacts with water to form an acidic solution.
Thus, the correct answer is acidic oxide.

Answer 2

The problem describes a reaction sequence involving a Lewis acid 'X', LiAlH₄, a gas 'Y', the formation of inorganic benzene, and the determination of the nature of compound 'Z'. Let's break down the solution step-by-step:

1. The Lewis acid 'X' reacts with LiAlH₄ to produce a highly toxic gas 'Y'. Commonly, BF₃ (Boron trifluoride) is a Lewis acid that reacts with LiAlH₄ to produce B₂H₆ (Diborane), which is known to be highly toxic.
2. The reaction of B₂H₆ with NH₃ leads to the formation of a compound referred to as "inorganic benzene". This compound is Borazine (B₃N₃H₆).
3. When 'Y' (B₂H₆) is burned in oxygen, it forms H₂O and a compound 'Z'.
   • The combustion reaction is:

B₂H₆ + 3O₂ → 3H₂O + B₂O₃

4. Thus, 'Z' is B₂O₃ (Boron trioxide).
5. B₂O₃ is known to be an acidic oxide. This is evidenced by its reaction with water to form boric acid (H₃BO₃). Hence, the solve concludes that compound 'Z' is an acidic oxide.