The correct arragement of O,P and N in order of increasing radii is

Options

A. `O lt N lt P`
B. `PltOltN`
C. `OltPltN`
D. `NltOltP`

Answer

To determine the correct arrangement of oxygen (O), phosphorus (P), and nitrogen (N) in order of increasing atomic radii, we can follow these steps:

### Step 1: Identify the Group and Period of Each Element
- **Nitrogen (N)** is in Group 15 and Period 2.
- **Oxygen (O)** is in Group 16 and Period 2.
- **Phosphorus (P)** is in Group 15 and Period 3.

### Step 2: Understand the Trend in Atomic Radii
- Atomic radii generally **decrease** from left to right across a period due to the increase in effective nuclear charge (Z effective), which pulls the electrons closer to the nucleus.
- Atomic radii generally **increase** from top to bottom in a group because additional electron shells are added, making the atom larger.

### Step 3: Compare the Elements
- **Oxygen (O)** and **Nitrogen (N)** are in the same period (Period 2). Since oxygen is to the right of nitrogen in the periodic table, it will have a smaller atomic radius than nitrogen.
- **Phosphorus (P)** is in Period 3 and is below nitrogen in Group 15. Therefore, phosphorus will have a larger atomic radius than nitrogen due to the addition of a new electron shell.
- Since phosphorus is also below oxygen in Group 16, it will have a larger atomic radius than oxygen as well.

### Step 4: Arrange the Elements in Order of Increasing Atomic Radii
Based on the trends:
- Oxygen (smallest radius)
- Nitrogen (medium radius)
- Phosphorus (largest radius)

Thus, the order of increasing atomic radii is:
**O < N < P**

### Final Answer
The correct arrangement of O, P, and N in order of increasing radii is:
**Oxygen < Nitrogen < Phosphorus** (O < N < P)

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