**asap** what is critical mass? ? a.) the greatest mass of any material that can stop a chain reaction b.) the greatest reaction that can sustain a chain reaction c.) the smallest mass of material that can sustain a chain reaction d.) the smallest mass of any material that can stop a chain reaction

Diffraction is when light is bent around obstructions. which of the these observation about clouds would indicate diffraction? a) after rain storms, you can sometimes see rainbows. b) clouds are white or gray and cannot be seen through. c) on a cloudy day, the temperature tends to be cooler than a sunny day. d) the edges of dark clouds appear lighter. this