When magnesium is burned in air, a powdery ash X is formed. X on dissolving in water forms Y.
What is the common name of the indigestion-relieving medicine which contains Y ?

Answer

To solve the question step by step, we can follow this process:

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

### Step 2: Determine the powdery ash (X)
The powdery ash formed from the burning of magnesium is magnesium oxide (MgO). So, we can denote this powdery ash as X:
- **X = MgO (Magnesium Oxide)**

### Step 3: Dissolve X in water
When magnesium oxide (X) is dissolved in water, it reacts to form magnesium hydroxide (Mg(OH)2). We can denote this compound as Y:
- **Y = Mg(OH)2 (Magnesium Hydroxide)**

### Step 4: Identify the common name of the medicine containing Y
Magnesium hydroxide (Y) is commonly used in indigestion-relieving medicines. The common name for such medicines is "antacids."

### Final Answer
The common name of the indigestion-relieving medicine which contains Y (magnesium hydroxide) is **antacid**.

---