Correct acidic order is

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Explanation

To determine the correct order of acidity among phenol and its substituted derivatives, we will follow these steps:

### Step 1: Understand the concept of acidity
Acidity is defined by the ability of a compound to donate a proton (H+). The more stable the conjugate base formed after deprotonation, the more acidic the compound is.

### Step 2: Analyze phenol
Phenol (C6H5OH) can donate a proton to form phenoxide ion (C6H5O−). The phenoxide ion is stabilized by resonance, which means that the negative charge can be delocalized over the aromatic ring. This stabilization increases the acidity of phenol.

### Step 3: Identify the effect of substituents
Substituents on the phenol ring can either be electron-withdrawing groups (EWGs) or electron-releasing groups (ERGs).

- **Electron-withdrawing groups** (like -NO2, -Cl) stabilize the negative charge on the phenoxide ion through resonance or inductive effects, thus increasing acidity.
- **Electron-releasing groups** (like -CH3, -OCH3) destabilize the negative charge on the phenoxide ion, thus decreasing acidity.

### Step 4: Determine the position of substituents
The position of the substituents (ortho, meta, or para) also affects the acidity:

- **Ortho and para positions**: ERGs have a stronger destabilizing effect due to hyperconjugation and inductive effects.
- **Meta position**: ERGs do not significantly affect the acidity because they do not stabilize or destabilize the phenoxide ion effectively.

### Step 5: Compare the acidity of substituted phenols
1. **Meta-substituted phenol**: Less affected by ERGs, hence more acidic than ortho and para substituted phenols.
2. **Para-substituted phenol**: More acidic than ortho-substituted phenol due to lesser destabilization from ERGs.
3. **Ortho-substituted phenol**: Least acidic due to maximum destabilization from ERGs.

### Step 6: Conclude the order of acidity
Based on the analysis, the order of acidity can be summarized as:
- Phenol > Meta-substituted phenol > Para-substituted phenol > Ortho-substituted phenol

### Final Order
Thus, the correct order of acidity is:
**Phenol > Meta-substituted phenol > Para-substituted phenol > Ortho-substituted phenol.**