Arrange these elements according to increasing electronegativity: Fr, F, Ca, N

What reaction is taking place? 02 + c3h8 = h20 + co2

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

Chemistry worksheet - i am not sure what they are asking for exactly?