A single atom of an element has 21 neutrons, 20 electrons, and 20 protons, which elementis it?

Two people each hold the end of a rope and create waves by moving their arms up and down. this wave is best classified as a transverse wave because a) both the rope particles and the wave are moving in the same direction. b) the wave is moving up and down as the particles of the rope move horizontally. c) the wave is moving horizontally as the particles of the rope move up and down. eliminate d) the wave is moving in a parallel direction with the motion of the person's arms.

What effect would average population growth have on land usage? a. urban use of land would rise to more than 30 percent of available land. b. industrial use of land would rise to more than 30 percent of available land. c. the percentage of available land used as cropland would stay the same. d. cropland would fall to about 10 percent of available land.

Need asap question 1 minerals are organic compounds. true false question 2 what vitamin can be found in foods like oranges, grapefruits, and broccoli? a. vitamin a b. vitamin k c.vitamin c d. vitamin d question 3 what are minerals? a. chemical elements that are needed for body processes. b. organic compounds that the body needs in small amounts to function properly. c. small molecules used to build proteins. d. an organic compound that is insoluble in water and includes fats. question 4 how many types of vitamins does the human body need? a. 15 b. 11 c. 13 d. 17 question 5 vitamins are a good source of energy. true false