Based on the following informations arrange four metals, A,B,C and D in order of increasing ability to act as reducing agents :
(I) Only C react with 1 M HCl to give `H_(2)`(g)
(II) When A is added to solution of the other metal ions, mettalic D is formed but not B or C

Options

A. `DgtAgtCgtB`
B. `AgtDgtCgtB`
C. `BgtDgtAgtC`
D. `DgtAgtBgtC`

Answer

To arrange the metals A, B, C, and D in order of increasing ability to act as reducing agents based on the given information, we can follow these steps:

### Step 1: Analyze the information provided
- **Information I**: Only metal C reacts with 1 M HCl to produce hydrogen gas (H₂). This indicates that C is capable of displacing hydrogen from the acid, suggesting that C is a strong reducing agent.
- **Information II**: When metal A is added to a solution of the other metal ions, metallic D is formed, but not B or C. This implies that A is more reactive than D, but less reactive than B and C.

### Step 2: Determine the relative reactivity of the metals
- From Information I, since C can react with HCl, it suggests that C is a strong reducing agent.
- From Information II, since A can displace D but not B or C, it indicates that A is less reactive than B and C but more reactive than D.

### Step 3: Summarize the reactivity order
Based on the analysis:
- C is the most reactive (strongest reducing agent).
- B is also reactive but less than C.
- A is less reactive than B and C but more reactive than D.
- D is the least reactive (weakest reducing agent).

### Step 4: Arrange the metals in order of increasing ability to act as reducing agents
Thus, the order of increasing ability to act as reducing agents is:
**D < A < B < C**

### Final Answer:
The final order of increasing ability to act as reducing agents is:
**D < A < B < C**

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