Which of the following reaction does not take place?

Options

A. `Cu + underset (conc) (2HC1) to CuC1_(2) + H_(2)`
B. `Cu + underset (conc) (2H_(2)SO_(4)) overset (Heat) (rarr) CuSO_(4) + SO_(2) + 2H_(2) O`
C. `3Cu + underset (dilute) (8HNO_(3)) to 3Cu(NO_(3))_(2) + 2NO + 4H_(2)O`
D. `Cu + 2AgNO_(3) to Cu(NO_(3))_(2) + 2Ag`

Answer

To determine which of the given reactions does not take place, we need to analyze each reaction based on the reactivity series of metals. The reactivity series helps us understand which metals can displace others in a chemical reaction.

### Step-by-Step Solution:

1. **Understanding the Reactivity Series**:
- The reactivity series ranks metals from most reactive to least reactive. In this series, metals that are higher can displace those that are lower from their compounds.

2. **Analyzing the First Reaction**:
- The first reaction involves copper reacting with hydrochloric acid (HCl) to produce copper chloride (CuCl2) and hydrogen gas (H2).
- Since copper is less reactive than hydrogen (as per the reactivity series), it cannot displace hydrogen from HCl. Therefore, this reaction **does not take place**.

3. **Analyzing the Second Reaction**:
- The second reaction involves copper reacting with copper sulfate (CuSO4).
- Here, there is no displacement reaction because copper is reacting with itself. Thus, this reaction **does take place**.

4. **Analyzing the Third Reaction**:
- The third reaction involves copper displacing silver (Ag) from silver nitrate (AgNO3) to form copper nitrate (Cu(NO3)2) and silver (Ag).
- Since copper is more reactive than silver, it can displace silver from its compound. Therefore, this reaction **does take place**.

5. **Analyzing the Fourth Reaction**:
- The fourth reaction involves copper reacting with oxygen (O2) to form copper oxide (CuO).
- This is a straightforward combination reaction where copper reacts with oxygen, and it **does take place**.

### Conclusion:
The reaction that does not take place is the first one, where copper attempts to displace hydrogen from hydrochloric acid.