The metal that does not displace hydrogen from an acid is

Options

A. Hg
B. Zn
C. Ca
D. Al

Answer

To determine the metal that does not displace hydrogen from an acid, 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. The more reactive a metal is, the more likely it is to displace hydrogen from acids.

### Step 2: Identify Metals in the Reactivity Series
Common metals in the reactivity series include:
- Sodium (Na)
- Calcium (Ca)
- Zinc (Zn)
- Iron (Fe)
- Aluminum (Al)
- Hydrogen (H)
- Copper (Cu)
- Mercury (Hg)

### Step 3: Analyze the Position of Hydrogen
In the reactivity series, hydrogen is positioned between aluminum and copper. This means that metals above hydrogen can displace it from acids, while metals below hydrogen cannot.

### Step 4: Identify the Metal That Does Not Displace Hydrogen
From the series, we can see that:
- Metals like zinc, iron, and aluminum can displace hydrogen from acids.
- However, metals like copper (Cu) and mercury (Hg) are less reactive than hydrogen.

### Step 5: Conclusion
The metal that does not displace hydrogen from an acid is **Mercury (Hg)**.

### Final Answer
**Mercury (Hg)** is the metal that does not displace hydrogen from an acid.

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