Why do non metal ions change from being soluble in solution to insoluble at the surface of the cathode

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

since electrons are negative the answer is neagtaive

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.