Which of the following will not displace hydrogen

Options

A. Ba
B. Pb
C. Hg
D. Sn

Explanation

To determine which of the given elements will not displace hydrogen, we need to refer to the electrochemical series, which ranks elements based on their standard reduction potentials (SRP). Elements with more negative SRP values can displace those with less negative or positive SRP values.

### Step-by-Step Solution:

1. **Understand the Electrochemical Series**:
- The electrochemical series is a list of elements arranged according to their standard reduction potentials. The more negative the SRP, the more easily the element can lose electrons and thus displace hydrogen.

2. **Identify the Elements**:
- Let's assume the elements in question are Beryllium (Be), Tin (Sn), Lead (Pb), and Mercury (Hg).

3. **Arrange the Elements Based on SRP**:
- In the electrochemical series, the elements can be arranged as follows (from more negative to less negative SRP):
- Beryllium (Be)
- Tin (Sn)
- Lead (Pb)
- Mercury (Hg)
- Hydrogen (H)

4. **Determine Displacement Ability**:
- An element can displace hydrogen if it is higher in the electrochemical series (more negative SRP) than hydrogen.
- Beryllium (Be), Tin (Sn), and Lead (Pb) can displace hydrogen because they are higher in the series compared to hydrogen.
- Mercury (Hg), however, is lower than hydrogen in the series.

5. **Conclusion**:
- Therefore, the element that will not displace hydrogen is **Mercury (Hg)**.

### Final Answer:
**Mercury (Hg) will not displace hydrogen.**

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