True or false: In a chemical reaction, atoms of elements cannot be present in the products if they were not present in the reactants. A
True

B
False

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:

the answer is na (sodium)