`H_2O_2` cannot act as

Options

A. oxidising agent
B. dehydrating agent
C. reducing agent
D. acid

Answer

To determine what `H2O2` (hydrogen peroxide) cannot act as, we need to analyze its properties and reactions. Here’s a step-by-step solution:

### Step 1: Identify the properties of `H2O2`
Hydrogen peroxide is known for its ability to act as both an oxidizing agent and a reducing agent. It can undergo various reactions depending on the conditions and the substances it interacts with.

### Step 2: Analyze its oxidizing properties
`H2O2` can act as an oxidizing agent. This means it can accept electrons and get reduced. For example:
\[ H_2O_2 + 2e^- \rightarrow 2OH^- \]
This shows that it can facilitate oxidation in other substances while being reduced itself.

### Step 3: Analyze its reducing properties
`H2O2` can also act as a reducing agent. It can oxidize itself to form oxygen gas:
\[ H_2O_2 \rightarrow O_2 + 2H^+ + 2e^- \]
This indicates that it can donate electrons, thus acting as a reducing agent.

### Step 4: Analyze its acidic properties
Hydrogen peroxide can exhibit weak acidic behavior. For instance, when it reacts with sodium hydroxide (NaOH), it forms sodium peroxide (Na2O2) and water:
\[ H_2O_2 + 2NaOH \rightarrow Na_2O_2 + 2H_2O \]
This reaction demonstrates that `H2O2` can act as an acid in this context.

### Step 5: Analyze its dehydrating properties
A dehydrating agent is typically a substance that can absorb water. However, `H2O2` does not act as a dehydrating agent because it decomposes to release water:
\[ 2H_2O_2 \rightarrow 2H_2O + O_2 \]
Since hydrogen peroxide itself produces water upon decomposition, it cannot absorb water.

### Conclusion
Based on the analysis, the correct answer is that `H2O2` cannot act as a dehydrating agent.

### Final Answer
`H2O2` cannot act as a dehydrating agent.