Which among `Na,K,Cs` and `Li` forms most stable hydride?

Explanation

To determine which among Na, K, Cs, and Li forms the most stable hydride, we need to analyze the stability of the hydrides formed by these alkali metals.

### Step-by-Step Solution:

1. **Understanding Hydride Formation**:
Hydrides are formed when alkali metals react with hydrogen. The general reaction can be represented as:
\[
2M + H_2 \rightarrow 2MH
...