Magnesium is burnt in the atmosphere of dinitrogen. The ash so produced is treated with water. The final products are

Options

A. `MgO+H_2`
B. `Mg(OH)_2`
C. `Mg(OH)_2+NH_3`
D. `MgH_2+O_2`

Answer

To solve the problem step by step, we will analyze the reactions involved when magnesium is burnt in an atmosphere of dinitrogen and the subsequent treatment of the ash with water.

### Step 1: Reaction of Magnesium with Dinitrogen
When magnesium (Mg) is burnt in the presence of dinitrogen (N₂), it primarily reacts with oxygen (O₂) from the air to form magnesium oxide (MgO) and with nitrogen to form magnesium nitride (Mg₃N₂).

The balanced reactions are:
1. \( 2Mg + O_2 \rightarrow 2MgO \)
2. \( 3Mg + N_2 \rightarrow Mg_3N_2 \)

### Step 2: Ash Produced
The ash produced from burning magnesium in the atmosphere of dinitrogen will contain both magnesium oxide (MgO) and magnesium nitride (Mg₃N₂).

### Step 3: Reaction of Ash with Water
Next, we treat the ash (which contains MgO and Mg₃N₂) with water (H₂O).

1. **Reaction of Magnesium Oxide with Water:**
\[ MgO + H_2O \rightarrow Mg(OH)_2 \]
This reaction produces magnesium hydroxide (Mg(OH)₂).

2. **Reaction of Magnesium Nitride with Water:**
\[ Mg_3N_2 + 6H_2O \rightarrow 3Mg(OH)_2 + 2NH_3 \]
This reaction produces magnesium hydroxide (Mg(OH)₂) and ammonia (NH₃).

### Step 4: Final Products
From the above reactions, we can summarize the final products:
- From magnesium oxide: \( Mg(OH)_2 \)
- From magnesium nitride: \( Mg(OH)_2 \) and \( NH_3 \)

Thus, the final products when the ash is treated with water are:
- Magnesium hydroxide (Mg(OH)₂)
- Ammonia (NH₃)

### Conclusion
The final products are:
- \( Mg(OH)_2 \)
- \( NH_3 \)