Antoine lavoisier is often referred to as the "father of modern chemistry". this is partly because of his discovery of the role of oxygen in combustion reactions but also his discovery that a) neutrons have no charge. b) the atom contains a positively-charged nucleus. c) the masses of the reactants and products are equal. d) atoms of the same element can have different masses.

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:

if you mean hydrogen and oxygen then water is the product