A change in means that a chemical reaction has occurred. A. the energy and mass

B. the kinds of atoms involved

C. the properties and identity of the reacting substances

D. the energy and kinds of atoms of the reacting substances

c

Explanation:

the properties and ideitity of the reacting substances

hope this elps

indicate valleys, hills, steepness and gentleness of slopes.

explanation:

contour lines on a map indicate elevation, or depth. numeric notations on contour lines refer to the level of elevation, or height about sea level.

the electrical  conductivity  of asolution  of an electrolyte is measured by determining the resistance of thesolution  between two flat or cylindrical electrodes separated by a fixed distance.