In a reaction, copper can displace:

Options

A. iron
B. magnesium
C. silver
D. All of these

Explanation

To determine which elements copper can displace in a reaction, we need to refer to the reactivity series of metals. Here’s a step-by-step solution:

### Step 1: Understand the Reactivity Series
The reactivity series is a list of metals arranged in order of decreasing reactivity. The more reactive a metal is, the more easily it can displace less reactive metals from their compounds.

### Step 2: Identify the Position of Copper
In the reactivity series, copper is positioned below hydrogen, which means it is less reactive than metals above it, such as potassium, sodium, zinc, and iron.

### Step 3: Determine Displacement Ability
Copper can displace metals that are less reactive than itself. Therefore, it can displace metals that are positioned below it in the reactivity series.

### Step 4: List Metals Copper Can Displace
Since copper is less reactive than metals like potassium, sodium, zinc, and iron, it cannot displace them. However, it can displace metals that are less reactive, such as:
- Silver (Ag)
- Gold (Au)

### Conclusion
In summary, copper can displace silver and gold from their compounds in a reaction.

---