Number of elements which form basic oxide is Magnesium, aluminium, carbon, sulphur, iron, potassium, zinc.

Explanation

To determine the number of elements from the given list that form basic oxides, we can follow these steps:

### Step 1: Identify the Elements
The elements provided are:
- Magnesium (Mg)
- Aluminium (Al)
- Carbon (C)
- Sulphur (S)
- Iron (Fe)
- Potassium (K)
- Zinc (Zn)

### Step 2: Classify the Elements
We need to classify these elements into metals and non-metals:
- **Metals**: Magnesium (Mg), Aluminium (Al), Iron (Fe), Potassium (K), Zinc (Zn)
- **Non-metals**: Carbon (C), Sulphur (S)

### Step 3: Understand Basic Oxides
Basic oxides are typically formed by metals. When these metal oxides react with water, they produce alkalis (basic solutions).

### Step 4: Identify Which Elements Form Basic Oxides
From our classification:
- **Metals that form basic oxides**:
- Magnesium (Mg) → forms Magnesium Oxide (MgO)
- Aluminium (Al) → forms Aluminium Oxide (Al2O3)
- Iron (Fe) → forms Iron Oxide (FeO or Fe2O3)
- Potassium (K) → forms Potassium Oxide (K2O)
- Zinc (Zn) → forms Zinc Oxide (ZnO)

### Step 5: Count the Elements that Form Basic Oxides
Now, we count the metals identified:
- Magnesium (Mg)
- Aluminium (Al)
- Iron (Fe)
- Potassium (K)
- Zinc (Zn)

This gives us a total of **5 elements** that form basic oxides.

### Final Answer
The number of elements which form basic oxides is **5**.

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