Help please I need help with this it says which one is it talking about

24-karat gold is considered to be pure gold. 18-karat gold is considered to be about 75% gold. what is 18-karat gold considered a mixture rather than a pure substance? a) it has a variable composition of other elements and minerals. b) its color is different than pure gold. c) the gold atoms are not arranged in a repeating pattern. d) it can be melted and transformed into a different substance.

This is a government controlled by one person with absolute power. question 3 options: communist democratic autocratic parliamentary

Which of the following items would serve as a primary source for a historian studiying the american civil war