Which of the following metal does not evolve hydrogen gas on reaction with dilute HCl?

Options

A. magnesium
B. iron
C. copper
D. aluminium

Explanation

To determine which metal does not evolve hydrogen gas when reacted with dilute hydrochloric acid (HCl), we can follow these steps:

### Step 1: Understand the Reactivity Series
The reactivity series is a list of metals arranged in order of decreasing reactivity. Metals that are more reactive than hydrogen can displace hydrogen from acids, while those that are less reactive cannot.

### Step 2: Identify the Metals in the Question
Let’s consider some common metals and their positions in the reactivity series:
- Magnesium (Mg)
- Iron (Fe)
- Aluminum (Al)
- Copper (Cu)
- Silver (Ag)
- Gold (Au)

### Step 3: Analyze Each Metal's Reactivity with HCl
- **Magnesium (Mg)**: More reactive than hydrogen, will evolve hydrogen gas.
- **Iron (Fe)**: More reactive than hydrogen, will evolve hydrogen gas.
- **Aluminum (Al)**: More reactive than hydrogen, will evolve hydrogen gas.
- **Copper (Cu)**: Less reactive than hydrogen, will not evolve hydrogen gas.
- **Silver (Ag)**: Less reactive than hydrogen, will not evolve hydrogen gas.
- **Gold (Au)**: Least reactive, will not evolve hydrogen gas.

### Step 4: Conclusion
From the analysis, we can conclude that copper (Cu) does not evolve hydrogen gas when reacted with dilute HCl because it is less reactive than hydrogen.

### Final Answer
The metal that does not evolve hydrogen gas on reaction with dilute HCl is **Copper (Cu)**.

---