Arrange the pairs in sequence in decreasing order of base and increasing order of basicity of an acid and the salts formed between an acid and base with equal basicity and acidity in their increasing order respectively.
(a) Sodium chloride
(b) Barium hydroxide, sulphuric acid
(c) Ferric phosphate
(d) Ferric hydroxide, hydrochloric acid
(e) Barium sulphate
(f) Sodium hydroxide, phosphoric acid

Options

A. dbfaec
B. fbdaec
C. dbfcea
D. fbdcea

Explanation

To solve the question, we need to arrange the given pairs in two sequences: one in decreasing order of basicity and the other in increasing order of acidity. Let's break it down step by step.

### Step 1: Identify the Acids and Bases
We have the following pairs:
1. **Sodium chloride (NaCl)** - This is a salt.
2. **Barium hydroxide (Ba(OH)₂), Sulphuric acid (H₂SO₄)** - Barium hydroxide is a strong base, and sulphuric acid is a strong acid.
3. **Ferric phosphate (FePO₄)** - This is a salt.
4. **Ferric hydroxide (Fe(OH)₃), Hydrochloric acid (HCl)** - Ferric hydroxide is a weak base, and hydrochloric acid is a strong acid.
5. **Barium sulphate (BaSO₄)** - This is a salt.
6. **Sodium hydroxide (NaOH), Phosphoric acid (H₃PO₄)** - Sodium hydroxide is a strong base, and phosphoric acid is a weak acid.

### Step 2: Determine Basicity and Acidity
- **Basicity**: Strong bases include NaOH and Ba(OH)₂, while weak bases include Fe(OH)₃.
- **Acidity**: Strong acids include HCl and H₂SO₄, while weak acids include H₃PO₄.

### Step 3: Arrange in Decreasing Order of Basicity
1. **Sodium hydroxide (NaOH)** - Strongest base.
2. **Barium hydroxide (Ba(OH)₂)** - Strong base.
3. **Ferric hydroxide (Fe(OH)₃)** - Weak base.

So, the decreasing order of basicity is:
- NaOH > Ba(OH)₂ > Fe(OH)₃

### Step 4: Arrange in Increasing Order of Acidity
1. **Phosphoric acid (H₃PO₄)** - Weak acid.
2. **Sulphuric acid (H₂SO₄)** - Strong acid.
3. **Hydrochloric acid (HCl)** - Strongest acid.

So, the increasing order of acidity is:
- H₃PO₄ < H₂SO₄ < HCl

### Step 5: Combine the Results
Now we can combine the results for the pairs:
1. **D: Ferric hydroxide (Fe(OH)₃), Hydrochloric acid (HCl)** - Weak base and strong acid.
2. **B: Barium hydroxide (Ba(OH)₂), Sulphuric acid (H₂SO₄)** - Strong base and strong acid.
3. **F: Sodium hydroxide (NaOH), Phosphoric acid (H₃PO₄)** - Strong base and weak acid.

### Final Arrangement
- For decreasing order of basicity: D (Fe(OH)₃, HCl) < B (Ba(OH)₂, H₂SO₄) < F (NaOH, H₃PO₄)
- For increasing order of acidity: F (NaOH, H₃PO₄) < B (Ba(OH)₂, H₂SO₄) < D (Fe(OH)₃, HCl)

### Step 6: Arrange Salts in Increasing Order
The salts formed between acids and bases of equal basicity and acidity are:
1. **Sodium chloride (NaCl)** - Formed from NaOH and HCl.
2. **Barium sulphate (BaSO₄)** - Formed from Ba(OH)₂ and H₂SO₄.
3. **Ferric phosphate (FePO₄)** - Formed from Fe(OH)₃ and H₃PO₄.

So, the increasing order of salts based on their formation is:
- NaCl < BaSO₄ < FePO₄

### Final Answer
The complete arrangement is:
1. **D (Ferric hydroxide, Hydrochloric acid)**
2. **B (Barium hydroxide, Sulphuric acid)**
3. **F (Sodium hydroxide, Phosphoric acid)**
4. **A (Sodium chloride)**
5. **E (Barium sulphate)**
6. **C (Ferric phosphate)**