I think it's Potassium iodide because it has the highest solubility at 25°C.
As against non-metals are the elements which are usually soft. ... Generally, the elements containing 1,2 or 3 electrons in the valence shell of their structure are known as metals. While the elements with 4, 5, 6 or 7 electrons in their outermost shell are known as non-metals.
