Which transition metal reduces steam to evolve hydrogen

Options

A. Mg
B. Fe
C. Sc
D. Pt

Explanation

To determine which transition metal can reduce steam to evolve hydrogen gas, we can analyze the options provided: Mg, Fe, Scandium, and Platinum.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- The question asks for a transition metal that can reduce steam (H2O) to produce hydrogen gas (H2). This typically involves a reaction where the metal reacts with water or steam.

2. **Analyzing the Options**:
- **Magnesium (Mg)**: Magnesium can react with steam to produce magnesium oxide (MgO) and hydrogen gas (H2). However, it is not a transition metal; it is an alkaline earth metal.
- **Iron (Fe)**: Iron can react with steam at high temperatures to produce iron oxide (Fe3O4 or Fe2O3) and hydrogen gas. The reaction can be represented as:
\[ Fe_2O_3 + 3H_2 \rightarrow 2Fe + 3H_2O \]
This shows that iron can indeed reduce steam to evolve hydrogen.
- **Scandium (Sc)**: Scandium is a transition metal, but it does not readily react with steam at normal conditions to produce hydrogen.
- **Platinum (Pt)**: Platinum is a noble metal and does not react with steam to produce hydrogen gas.

3. **Conclusion**:
- Among the given options, the transition metal that can reduce steam to evolve hydrogen gas is **Iron (Fe)**.

### Final Answer:
The transition metal that reduces steam to evolve hydrogen is **Iron (Fe)**.