Which of the following will not act as oxidising agents?

Options

A. `CrO_(3)`
B. `MnO_(3)`
C. `WO_(3)`
D. `CrO_(4)^(3-)`

Answer

To determine which of the given compounds will not act as an oxidizing agent, we need to analyze the oxidation states of the elements involved and their tendencies to undergo reduction. Here’s a step-by-step solution:

### Step 1: Identify the Compounds
The compounds given in the question are:
1. CrO3 (Chromium trioxide)
2. MnO3 (Manganese trioxide)
3. WO3 (Tungsten trioxide)
4. CrO4^3- (Chromate ion)

### Step 2: Determine the Oxidation States
Next, we calculate the oxidation states of the central metal in each compound:
- **CrO3**: Chromium (Cr) has an oxidation state of +6.
- **MnO3**: Manganese (Mn) has an oxidation state of +6.
- **WO3**: Tungsten (W) has an oxidation state of +6.
- **CrO4^3-**: In the chromate ion, Chromium (Cr) has an oxidation state of +6.

### Step 3: Analyze the Oxidizing Ability
An oxidizing agent is a substance that can gain electrons and be reduced. Generally, elements in higher oxidation states are better oxidizing agents because they can easily be reduced to lower oxidation states. However, heavier elements tend to be more stable in their higher oxidation states and do not reduce easily.

### Step 4: Compare the Elements
- **Chromium (Cr)** and **Manganese (Mn)** are transition metals that can exist in multiple oxidation states and can be reduced.
- **Tungsten (W)**, being a heavier element, prefers to remain in its higher oxidation state (+6) and is less likely to be reduced to a lower oxidation state.

### Step 5: Conclusion
Since tungsten (W) in WO3 is less likely to act as an oxidizing agent due to its stability in the +6 oxidation state, it will not act as a good oxidizing agent compared to the others.

Thus, the answer is:
**WO3 (Tungsten trioxide) will not act as an oxidizing agent.**