Arrange the pairs in sequence in decreasing order of basicity of an acid and acidity of a base followed by the normal salts formed by the given acid base pairs in the same order respectively.
(a) Acetic acid, ammonium hydroxide
(b) Oxalic acid, barium hydroxide
(c) Phosphoric acid, aluminium hydroxide
(d) Barium oxalate
(e) Ammonium acetate
(f) Aluminium phosphate

Options

A. adcfe
B. cbafde
C. adcebf
D. cdaebf

Explanation

To solve the problem of arranging the given acid-base pairs in decreasing order of basicity of an acid and acidity of a base, followed by the normal salts formed by these pairs, we will follow these steps:

### Step 1: Identify the Acids and Bases
We have the following pairs:
- (a) Acetic acid (CH₃COOH) and Ammonium hydroxide (NH₄OH)
- (b) Oxalic acid (C₂H₂O₄) and Barium hydroxide (Ba(OH)₂)
- (c) Phosphoric acid (H₃PO₄) and Aluminium hydroxide (Al(OH)₃)

### Step 2: Determine the Basicity of the Acids
The basicity of an acid refers to the number of hydrogen ions (H⁺) it can donate. The acids in order of decreasing basicity are:
1. Phosphoric acid (H₃PO₄) - can donate 3 H⁺ ions
2. Oxalic acid (C₂H₂O₄) - can donate 2 H⁺ ions
3. Acetic acid (CH₃COOH) - can donate 1 H⁺ ion

### Step 3: Determine the Acidity of the Bases
The acidity of a base refers to its ability to accept protons. The bases in order of decreasing acidity are:
1. Aluminium hydroxide (Al(OH)₃) - amphoteric, can react with acids and bases
2. Barium hydroxide (Ba(OH)₂) - strong base, readily dissociates in water
3. Ammonium hydroxide (NH₄OH) - weak base

### Step 4: Arrange the Pairs
Now we can arrange the pairs based on the basicity of the acids and the acidity of the bases:
1. Phosphoric acid (H₃PO₄) and Aluminium hydroxide (Al(OH)₃)
2. Oxalic acid (C₂H₂O₄) and Barium hydroxide (Ba(OH)₂)
3. Acetic acid (CH₃COOH) and Ammonium hydroxide (NH₄OH)

### Step 5: Identify the Normal Salts Formed
Next, we identify the normal salts formed from these acid-base pairs:
1. From Phosphoric acid and Aluminium hydroxide, we get Aluminium phosphate (AlPO₄).
2. From Oxalic acid and Barium hydroxide, we get Barium oxalate (BaC₂O₄).
3. From Acetic acid and Ammonium hydroxide, we get Ammonium acetate (NH₄C₂H₃O₂).

### Final Arrangement
Now we can summarize the final arrangement in decreasing order:
1. Phosphoric acid (H₃PO₄) - Aluminium hydroxide (Al(OH)₃) → Aluminium phosphate (AlPO₄)
2. Oxalic acid (C₂H₂O₄) - Barium hydroxide (Ba(OH)₂) → Barium oxalate (BaC₂O₄)
3. Acetic acid (CH₃COOH) - Ammonium hydroxide (NH₄OH) → Ammonium acetate (NH₄C₂H₃O₂)

### Final Sequence
The final sequence is:
- C (Phosphoric acid, Aluminium hydroxide) → F (Aluminium phosphate)
- B (Oxalic acid, Barium hydroxide) → D (Barium oxalate)
- A (Acetic acid, Ammonium hydroxide) → E (Ammonium acetate)

Thus, the correct order is: C, F, B, D, A, E.