You may have heard about quarks and quark theory. Quarks are elementary particles that make up larger particles, called hadrons. Protons and neutrons are two examples of hadrons. Research quark theory and how quarks might fit into our atomic model.

Quarks are supposed to be in the atomic nucleus since they combine to form the nucleons : Protons and neutrons.

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.

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