On adding `KMnO_(4)` to cold conc. `H_(2)SO_(4),` it gives

Options

A. `MnO_2`
B. `Mn_2O_3`
C. `Mn_2O_7`
D. `MnO_3`

Answer

To solve the question regarding the reaction of potassium permanganate (KMnO4) with cold concentrated sulfuric acid (H2SO4), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants in this reaction are potassium permanganate (KMnO4) and cold concentrated sulfuric acid (H2SO4).

2. **Write the Reaction**:
- When KMnO4 is added to cold concentrated H2SO4, it reacts to form manganese(VII) oxide (Mn2O7), potassium sulfate (K2SO4), and water (H2O).
- The balanced chemical equation for this reaction can be written as:
\[ 2 KMnO_4 + 3 H_2SO_4 \rightarrow K_2SO_4 + 2 Mn_2O_7 + 3 H_2O \]

3. **Identify the Main Product**:
- The main product formed in this reaction is manganese(VII) oxide (Mn2O7), which is a dark brown liquid.

4. **Heating of Mn2O7**:
- If the Mn2O7 is further heated, it can decompose to form manganese dioxide (MnO2) and oxygen gas (O2):
\[ 2 Mn_2O_7 \rightarrow 4 MnO_2 + O_2 \]

5. **Conclusion**:
- The primary product when KMnO4 is added to cold concentrated H2SO4 is Mn2O7. Therefore, the correct answer to the question is option C, which corresponds to the formation of manganese(VII) oxide.

### Final Answer:
- The reaction of KMnO4 with cold concentrated H2SO4 gives Mn2O7.