Arrange pH of the given compounds in decreasing order:
(1) Phenol
(2) Ethyl alcohol
(3) Formic acid
(4). Benzoic acid

Options

A. `1gt2gt3gt4`
B. `2gt1gt4gt3`
C. `3gt2gt4gt1`
D. `4gt3gt1gt2`

Answer

To arrange the pH of the given compounds (Phenol, Ethyl alcohol, Formic acid, and Benzoic acid) in decreasing order, we need to analyze their acidic strengths first. The higher the pH, the lower the acidic strength. Here’s a step-by-step solution:

### Step 1: Identify the Compounds
The compounds to be analyzed are:
1. Phenol (C6H5OH)
2. Ethyl alcohol (C2H5OH)
3. Formic acid (HCOOH)
4. Benzoic acid (C6H5COOH)

### Step 2: Determine the Acidic Strength
The acidic strength of these compounds can be compared based on their ability to donate protons (H+ ions).

- **Phenol**: It can donate a proton to form phenoxide ion (C6H5O-). The phenoxide ion is stabilized by resonance, making phenol relatively acidic.

- **Formic Acid**: It is a weak acid that can dissociate to release H+ ions. Its conjugate base (formate ion) is stable due to resonance.

- **Benzoic Acid**: Similar to formic acid, it can release H+ ions, but the presence of the benzene ring (which is an electron-donating group) decreases its acidity compared to formic acid.

- **Ethyl Alcohol**: It is not an acid in the same sense as the others; it does not readily donate protons, making it the least acidic among the four.

### Step 3: Rank the Compounds by Acidic Strength
Based on the above analysis, we can rank the compounds in order of decreasing acidic strength:
1. **Phenol** (most acidic)
2. **Formic Acid**
3. **Benzoic Acid**
4. **Ethyl Alcohol** (least acidic)

### Step 4: Convert Acidic Strength to pH Order
Since pH is inversely related to acidic strength, the order of decreasing pH (from highest to lowest) will be the reverse of the acidic strength order:
1. **Ethyl Alcohol** (highest pH)
2. **Benzoic Acid**
3. **Formic Acid**
4. **Phenol** (lowest pH)

### Final Answer
The order of pH in decreasing order is:
**Ethyl Alcohol > Benzoic Acid > Formic Acid > Phenol**

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