When megnesium is burnt in air, a white ash remains as left over. Aqueous solution of this white ash turns red litmus blue. The formula of the white ash and type of reaction respectively are

Options

A. MgO, non-redox reaction
B. Mgo, redox reaction
C. `Mg(OH)_(2)`, decomposition reaction
D. MgO, displacement reaction

Answer

To solve the question, we will break it down into steps:

### Step 1: Identify the reaction taking place
When magnesium (Mg) is burned in air, it reacts with oxygen (O₂) to form magnesium oxide (MgO).

### Step 2: Write the balanced chemical equation
The balanced chemical equation for the reaction is:
\[ 2 \text{Mg} + \text{O}_2 \rightarrow 2 \text{MgO} \]

### Step 3: Identify the white ash
The white ash that remains after burning magnesium is magnesium oxide (MgO).

### Step 4: Determine the nature of the solution
When magnesium oxide is dissolved in water, it forms an alkaline solution, which turns red litmus paper blue. This indicates that the solution is basic.

### Step 5: Identify the type of reaction
In this reaction, magnesium is oxidized from an oxidation state of 0 to +2, while oxygen is reduced from 0 to -2. Since both oxidation and reduction occur simultaneously, this is classified as a redox reaction.

### Final Answer
The formula of the white ash is \( \text{MgO} \) and the type of reaction is a redox reaction.

---