In which of the following properties hydrogen does not show similarity with alkali metals?

Options

A. Electropositive character
B. Reducing nature
C. Electronic configuration `(ns^(1))`
D. Diatomic nature of molecule

Explanation

To solve the question of which property hydrogen does not show similarity with alkali metals, we can analyze each option provided.

### Step 1: Understand the properties of hydrogen and alkali metals
- **Electropositive character**: Both hydrogen and alkali metals (like sodium, potassium) exhibit electropositive character. They can lose electrons to form positive ions.
- **Reducing nature**: Hydrogen can act as a reducing agent, similar to alkali metals which also have reducing properties.
- **Electronic configuration**: Hydrogen has an electronic configuration of 1s¹, while alkali metals have an outer electronic configuration of ns¹ (where n is the principal quantum number). This shows similarity in their outermost electron configuration.
- **Diatomic nature**: Hydrogen exists as a diatomic molecule (H₂), while alkali metals exist as monoatomic species (Na, K, etc.). This is a significant difference.

### Step 2: Identify the property that is different
From the analysis:
- Hydrogen shows similarity with alkali metals in terms of electropositive character, reducing nature, and electronic configuration.
- However, hydrogen does not show similarity in its molecular form, as it exists as H₂ (diatomic) while alkali metals are monoatomic.

### Conclusion
The property in which hydrogen does not show similarity with alkali metals is its diatomic nature of the molecule.

**Final Answer**: Hydrogen does not show similarity with alkali metals in terms of diatomic nature of the molecule.

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