Question

A small amount of a solid unknown compound was placed into a test tube containing isopropanol. The solid floats on top of the liquid isopropanol. Is this unknown compound considered to be soluble or insoluble?

Answer 1

The unknown solid did not dissolve into the isopropanol , therefore it is insoluble. 

Answer 2

Answer:

It is insoluble

Explanation:

Solubility and floatability are different concepts:

Solubility depends of the polarity and chemical characteristics of the solute and solvent.  

Floatability depends of the density and volume of the solid, and the density of the liquid it's in.

Given that the unknown solid didn't disolve (you can see it on top of the liquid), it is insoluble in isopropanol.