Which of the following statements is not true for Al and B ?

Options

A. They burn in oxygen to give oxides at higher temperature
B. Their halides are Lewis acids
C. They combine with nitrogens to form nitrides
D. They react with HCl to give chloride.

Explanation

To determine which statement is not true for Aluminium (Al) and Boron (B), let's analyze each option step by step.

### Step 1: Analyze Statement 1
**Statement 1:** They burn in Oxygen to give Oxides at higher temperature.

- **Explanation:** Both Aluminium and Boron can react with oxygen to form their respective oxides (Al2O3 for Aluminium and B2O3 for Boron) when heated to high temperatures.
- **Conclusion:** This statement is **true**.

### Step 2: Analyze Statement 2
**Statement 2:** Halides are Lewis Acids.

- **Explanation:** Both Aluminium halides (like AlCl3) and Boron halides (like BCl3) are known to act as Lewis acids. They can accept electron pairs due to their electron-deficient nature.
- **Conclusion:** This statement is **true**.

### Step 3: Analyze Statement 3
**Statement 3:** They are combined with Nitrogens to form Nitrides.

- **Explanation:** Both Aluminium and Boron can react with nitrogen to form nitrides (AlN for Aluminium and BN for Boron). This is a well-known reaction.
- **Conclusion:** This statement is **true**.

### Step 4: Analyze Statement 4
**Statement 4:** They react with HCl to give Chloride.

- **Explanation:** Aluminium reacts with HCl to form Aluminium chloride (AlCl3) and hydrogen gas. However, Boron does not react with HCl to form a chloride; instead, it forms boron trichloride (BCl3) under specific conditions, but it does not react directly in the same manner as Aluminium. Therefore, this statement is misleading as it implies both react similarly.
- **Conclusion:** This statement is **not true**.

### Final Conclusion
The statement that is not true for Aluminium and Boron is **Statement 4**: "They react with HCl to give Chloride."

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