Answer:
D. Sweat evaporates from your skin
Explanation:
A physical change is a reversible process, no new substance is formed. A physical change does not affect the chemical composition of a substance.
Sweat evaporation from the skin is a physical change, because the change that occur is merely a change of state, Liquid to Gaseous state, no new substance is formed.
Answer:
The periodic table of elements arranges all of the known chemical elements in an informative array. Elements are arranged from left to right and top to bottom in order of increasing atomic number. Order generally coincides with increasing atomic mass. ... For instance, all the group 18 elements are inert gases.
Explanation:
The oxidation is occurring on Calcium ions as it release one electron and reduction will be occurring on fluorine ion as it accepts one electron.
<u>Explanation:</u>
An element will undergo oxidation and form a positive ion on releasing one or more electrons from its valence shell. While reduction is occurred in a chemical reaction, then the element will be forming a negative ion with the acceptance of one or more electrons in its valence shell.
So in the given process of calcium fluoride, the one electron from the valence shell of calcium will be released making it as 
ions and this is termed as oxidation process. This one electron will be getting accepted by the fluorine ion and thus it will convert to 
ions. This process of acceptance of electrons is termed as reduction.
It has to be a metal, it can't be anything else.
