Which of the following are reducing agents:-

Options

A. A,D
B. A,B,E
C. A,B,D,E
D. All (A to E)

Answer

To determine which of the given compounds are reducing agents, we need to understand what a reducing agent is. A reducing agent is a substance that donates electrons to another substance, thereby reducing it while itself being oxidized.

Let's analyze each option step-by-step:

1. **Lithium (Li)**:
- Lithium is an alkali metal.
- Alkali metals are known for their strong reducing properties due to their low ionization energy.
- Lithium has a very low ionization energy and high hydration energy, making it a very strong reducing agent.
- **Conclusion**: Lithium is a reducing agent.

2. **Zinc (Zn)**:
- Zinc is often considered to act as a reducing agent in some reactions, but it can also act as an oxidizing agent depending on the context.
- In general, zinc is not classified as a strong reducing agent compared to alkali metals.
- **Conclusion**: Zinc is not a strong reducing agent.

3. **Cerium (Ce)**:
- Cerium in its +4 oxidation state (Ce^4+) is known to be an oxidizing agent.
- It tends to accept electrons rather than donate them.
- **Conclusion**: Cerium (Ce^4+) is not a reducing agent.

4. **Europium (Eu)**:
- Europium in the +2 oxidation state (Eu^2+) has the electronic configuration of [Xe] 4f^7 5d^1 6s^2.
- When it loses one electron to become Eu^3+, it donates an electron, thus acting as a reducing agent.
- **Conclusion**: Europium (Eu^2+) is a reducing agent.

5. **Gadolinium (Gd)**:
- Gadolinium in the +2 oxidation state (Gd^2+) can also act as a reducing agent due to its ability to donate electrons.
- However, it is less commonly discussed than lithium and europium in this context.
- **Conclusion**: Gadolinium (Gd^2+) can be considered a reducing agent.

**Final Answer**: The reducing agents among the given options are:
- A: Lithium (Li)
- D: Europium (Eu^2+)