Amixture (is/is not)a chemical combining of substances

is not

Explanation:

a mixture is when two elements bond together but do not physically combine

when elements physically combine it is a compound such as H2O

which is a compound of 2 hydrogen and 1 oxygen while a mixture would be Air because air is made up of many elements but they are not physically connected with one another.

i think its 100

i hope this !