Which of the following is the atomic number of an element that forms basic oxide?

Options

A. 18
B. 17
C. 19
D. 15

Explanation

To determine the atomic number of an element that forms a basic oxide, we need to identify which elements typically form basic oxides. Basic oxides are generally formed by metals. Here’s a step-by-step solution:

### Step 1: Understanding Basic and Acidic Oxides
- Basic oxides are formed by metals, while acidic oxides are formed by non-metals.
- Therefore, we need to look for a metal among the given atomic numbers.

### Step 2: Identifying the Elements Corresponding to Given Atomic Numbers
- The atomic numbers provided are 15, 17, 18, and 19.
- Let's identify the elements:
- Atomic number 15 corresponds to Phosphorus (P).
- Atomic number 17 corresponds to Chlorine (Cl).
- Atomic number 18 corresponds to Argon (Ar).
- Atomic number 19 corresponds to Potassium (K).

### Step 3: Classifying the Elements
- Phosphorus (P), Chlorine (Cl), and Argon (Ar) are non-metals.
- Potassium (K) is a metal.

### Step 4: Conclusion
- Since only metals form basic oxides, we conclude that the element with atomic number 19, which is Potassium (K), forms a basic oxide.
- The oxide formed by Potassium is K2O, which is basic in nature.

### Final Answer
- The atomic number of the element that forms a basic oxide is **19** (Potassium).

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