Metal `M+"air" overset(delta)(to)Aoverset(H_(2)O)(to)Boverset(HCl)(to)` White fumes, Metal M can be:

Options

A. `Le, Mg or Al`
B. `Li, Al or K`
C. `Na, K or Mg`
D. `Li, Na or K`

Answer

To solve the problem, we need to identify the metal \( M \) that reacts with air to form a compound \( A \), which upon hydrolysis with water forms a compound \( B \), and then reacts with hydrochloric acid (HCl) to produce white fumes. The presence of white fumes indicates the formation of ammonium chloride (NH4Cl).

### Step-by-Step Solution:

1. **Identify the Reaction with Air**:
- Metal \( M \) reacts with air. This generally means it reacts with oxygen and possibly nitrogen.
- The product \( A \) formed could be a metal oxide or a metal nitride.

2. **Hydrolysis with Water**:
- The product \( A \) then reacts with water to form \( B \).
- Since we are looking for a compound that can lead to the formation of ammonia (NH3), \( B \) must be a compound that can produce ammonia upon hydrolysis.

3. **Reaction with HCl**:
- The compound \( B \) reacts with HCl to produce white fumes, which indicates the formation of ammonium chloride (NH4Cl).
- This suggests that \( B \) must contain nitrogen in a form that can yield ammonia.

4. **Possible Metals**:
- We consider metals that can react with air to form nitrides or oxides that can hydrolyze to produce ammonia.
- Magnesium (Mg), Lithium (Li), and Aluminum (Al) are potential candidates because they can form nitrides or hydroxides that can react with HCl to produce NH4Cl.

5. **Verification**:
- Let's verify with Magnesium:
- \( \text{Mg} + \text{O}_2 \rightarrow \text{MgO} \) (or possibly a nitride)
- \( \text{MgO} + \text{H}_2O \rightarrow \text{Mg(OH)}_2 \) (or a reaction leading to NH3)
- \( \text{Mg(OH)}_2 + \text{HCl} \rightarrow \text{NH}_4\text{Cl} \) (producing white fumes)
- Similar reactions can be checked for Lithium and Aluminum.

6. **Conclusion**:
- Since all three metals (Mg, Li, Al) can lead to the formation of white fumes through the production of NH4Cl, we conclude that the metal \( M \) can be Magnesium, Lithium, or Aluminum.

### Final Answer:
The metal \( M \) can be: **Magnesium (Mg), Lithium (Li), or Aluminum (Al)**.