Two solutions are added together and the new solution becomes hot. This tells you that
A. a chemical change is taking place
B. the solutions are not soluble
C. the physical properties are the same
D. a gas is being produced

A

Explanation:

when certain chemical reactions are occurring, heat is evolved and that is what is termed exothermic reaction.

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation: