Which of these accurately describes a chemical reaction? a. products and reactants combine to form new substances. b. products combined to form reactants c. reactants combine to form products d. products and reactants combine to form new reactants.

Answer is: C. Reactants combine to form products.

In a chemical reaction, chemical bonds are forming and breaking and this cause the transformation of one group of chemical substances to another

For example synthesis of water from its elements: 2H₂ + O₂ → 2H₂O, nonpolar bonds between hydrogen and oxygen atoms (reactants) are breaking and new polar bonds are forming between hydrogen and oxygen in molecule of water (product).

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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