Arrange the following compounds in the order of valency of a positive radical.
(i) `A(H_2PO_4)_2`
(ii) `B_2O` (iii) `C_2(SO_4)_3`

Options

A. (iii) `gt` (i) `gt` (ii)
B. (iii) `gt` (ii) `gt` (i)
C. (ii) `gt` (i) `gt` (iii)
D. `(i) gt (ii) gt (iii)`

Explanation

To arrange the given compounds in the order of valency of the positive radical, we need to determine the valency of the positive ions in each compound. Let's analyze each compound step by step.

### Step 1: Analyze Compound A, \( (H_2PO_4)_2 \)

1. The compound \( (H_2PO_4)_2 \) consists of two \( H_2PO_4^- \) ions.
2. Each \( H_2PO_4^- \) ion has a charge of -1.
3. Therefore, two \( H_2PO_4^- \) ions contribute a total charge of -2.
4. To balance this negative charge, the positive radical must have a charge of +2.
5. Thus, the valency of the positive radical in compound A is **+2**.

### Step 2: Analyze Compound B, \( B_2O \)

1. The compound \( B_2O \) consists of two B atoms and one O atom.
2. Oxygen typically has a charge of -2.
3. Since there is one oxygen atom with a -2 charge, the total charge contributed by oxygen is -2.
4. To balance this, the two B atoms must collectively have a charge of +2.
5. Therefore, each B atom has a charge of +1 (since \( 2 \times +1 = +2 \)).
6. Thus, the valency of the positive radical in compound B is **+1**.

### Step 3: Analyze Compound C, \( C_2(SO_4)_3 \)

1. The compound \( C_2(SO_4)_3 \) consists of two C atoms and three sulfate ions \( (SO_4^{2-}) \).
2. Each sulfate ion has a charge of -2.
3. Therefore, three sulfate ions contribute a total charge of -6.
4. To balance this negative charge, the positive radical must have a charge of +6.
5. Since there are two C atoms, each C atom must have a charge of +3 (since \( 2 \times +3 = +6 \)).
6. Thus, the valency of the positive radical in compound C is **+3**.

### Step 4: Arrange the Compounds

Now that we have determined the valencies of the positive radicals:
- Compound A: +2
- Compound B: +1
- Compound C: +3

We can arrange them in the order of decreasing valency of the positive radical:
1. C: +3
2. A: +2
3. B: +1

### Final Answer

The order of the compounds in the decreasing order of the valency of the positive radical is:
**C, A, B**