How does an atom become a positively charged ion?
A. by gaining one or more electrons
B. by gaining one or more neutrons
C. by losing one or more neutrons
D. by losing one or more electrons

 Your answer would be D.  A neutral atom would become positively charged when they lose electrons because electrons are negatively charged.  Removing some of these negative charges causes the atom to become more positively charged.  Hope this has helped you :D

c is the answer because when something is left after something evaporates that shows the chemical change.