Which one of the following properties shows that hydrogen resembles alkali metals ?

Options

A. It shows metallic character like alkali metals.
B. It is diatomic llike alkali metals.
C. Its ionization energy is of the same order as that of alkali metals.
D. When hydrogen halides and alkali metal halides are electrolysed, hydrogen and alkali metals are liberated at the cathode.

Explanation

To determine which property shows that hydrogen resembles alkali metals, we can analyze the given options step by step.

### Step 1: Analyze the first property - Metallic Character
- **Statement**: Hydrogen shows metallic character like alkali metals.
- **Analysis**: Alkali metals (like sodium, potassium) are known for their metallic character, which includes properties such as luster, malleability, and conductivity. Hydrogen, however, is a non-metal and exists as a gas at room temperature. Therefore, it does not exhibit metallic character.
- **Conclusion**: This statement is incorrect.

### Step 2: Analyze the second property - Diatomic Nature
- **Statement**: Hydrogen is diatomic like alkali metals.
- **Analysis**: Hydrogen exists as H2 molecules, meaning it is diatomic. However, alkali metals exist as single atoms in their elemental state (e.g., Na, K). Thus, while hydrogen is diatomic, alkali metals are not.
- **Conclusion**: This statement is also incorrect.

### Step 3: Analyze the third property - Ionization Energy
- **Statement**: Hydrogen's ionization energy is of the same order as that of alkali metals.
- **Analysis**: The ionization energy of hydrogen is significantly higher than that of alkali metals. Alkali metals have low ionization energies because they readily lose their outermost electron. In contrast, hydrogen requires more energy to lose its single electron.
- **Conclusion**: This statement is incorrect.

### Step 4: Analyze the fourth property - Electrolysis of Halides
- **Statement**: When hydrogen halides and alkali metal halides are electrolyzed, hydrogen goes to the cathode and alkali metals are liberated at the cathode.
- **Analysis**: During the electrolysis of hydrogen halides (e.g., HCl), hydrogen ions (H+) are reduced at the cathode to form hydrogen gas (H2). In the case of alkali metal hydrides (e.g., NaH), sodium ions (Na+) are also reduced at the cathode to form sodium metal. This similarity in behavior during electrolysis is a significant resemblance between hydrogen and alkali metals.
- **Conclusion**: This statement is correct.

### Final Answer:
The property that shows hydrogen resembles alkali metals is: **When hydrogen halides and alkali metal halides are electrolyzed, hydrogen goes to the cathode and alkali metals are liberated at the cathode.**