1. Think about chemical reactions in your everyday life. How might it help to know about different types of chemical reactions? 2. Consider the equation A + B --> AB. Can you think of another situation you have encountered (outside of this course) where a process in this general form takes place?
3. Describe a chemical reaction that you have recently witnessed. How did you know that it was a chemical reaction? What type of chemical reaction do you think it was?

the correct answer, according to e2020, is the second choice there is an occluded front in region a and a cold front in region b.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.