Question

What are two solids that float on their liquids?

Answer 1

Arsenic and Silicon

Explanation:

The most obvious answer, of course, is water; and there are a number of compounds or alloys which are less dense in their sold state than in their liquid state.

In terms of pure elements this list is restricted to 5 elements:
Arsenic, Bismuth,Gallium, Germanium, and Silicon