Which of the following is not an example of single displacement reaction ?

Options

A. `CuO + H_2 to H_2O + Cu`
B. `Zn+ CuSO_4 to ZnSO_4 +Cu`
C. `4NH_3 + 5O_2 to 4NO + 6H_2O`
D. `Zn + 2HCl to H_2 + ZnCl_2`

Explanation

To determine which of the following options is not an example of a single displacement reaction, we first need to understand what a single displacement reaction is.

### Step 1: Define Single Displacement Reaction
A single displacement reaction is a type of chemical reaction where one element displaces another element in a compound. The general form of a single displacement reaction can be represented as:
\[ A + BC \rightarrow AC + B \]
Here, element A displaces element B from the compound BC.

### Step 2: Analyze Each Option
Now, let’s analyze each of the given options to identify which one does not represent a single displacement reaction.

**Option A:**
\[ CuO + H_2 \rightarrow H_2O + Cu \]
In this reaction, hydrogen (H) displaces copper (Cu) from copper oxide (CuO). This is a single displacement reaction.

**Option B:**
\[ CuSO_4 + Zn \rightarrow ZnSO_4 + Cu \]
In this reaction, zinc (Zn) displaces copper (Cu) from copper sulfate (CuSO₄). This is also a single displacement reaction.

**Option C:**
\[ 2NH_3 \rightarrow NO + H_2O \]
In this reaction, ammonia (NH₃) is breaking down into nitrogen monoxide (NO) and water (H₂O). There is no displacement of one element by another; instead, it is a decomposition reaction. Therefore, this is not a single displacement reaction.

**Option D:**
\[ Zn + 2HCl \rightarrow H_2 + ZnCl_2 \]
In this reaction, zinc (Zn) displaces hydrogen (H) from hydrochloric acid (HCl). This is a single displacement reaction.

### Conclusion
Based on the analysis, **Option C** is not an example of a single displacement reaction.

### Summary of the Solution
- **Single Displacement Reaction:** An element displaces another in a compound.
- **Option A:** Single displacement (H displaces Cu).
- **Option B:** Single displacement (Zn displaces Cu).
- **Option C:** Not a single displacement (decomposition reaction).
- **Option D:** Single displacement (Zn displaces H).
- **Final Answer:** Option C is not a single displacement reaction.