Oxygen has an atomic number of 8. the n = 1 energy level has two electrons, and the n = 2 energy level has six electrons. oxygen's valence is
+2
-2
+1
-1

Which of the following is an example of a tissue on the digestive system a.the stomach b.smooth muscle that lines the stomach c.nerve cells in the stomach d. enzyme molecules in the stomach

Rachel ate a piece of fruit and happened to drop the seeds in her backyard. after a few weeks, she saw a small plant with flowers growing in the backyard. which group does this plant belong to? a. angiosperms b. gymnosperms c. pteridophytes d. bryophytes e. chytrids

Which feature of a human community is similar to a niche in a biological community