when galaxies move away from us they appear to have a "red shift" in color. explain why this happens.

Which statement best describes resistance? resistance is a. how well a current will flow in a material and is measured in volts. b. how well a material conducts an electrical charge and is measured in ohms. c. the ability of a material to attract a positive charge to create a current. d. the ability of a material to repel neutral charges and is measured in ohms.

Which type of microscope would allow the viewer to see ribosomes inside a cell?

Give one example to show that when substances are mixed, it may result in a chemical or a physical change depending on the conditions.