Why are other materials of lower density typically poorer thermal conductors compared to materials of higher density

When a comet collides with earth, it adds material to our planet and causes great damage. therefore, a collision like this is a a. destructive force b. constructive force c. geologic process and event d. constructive and destructive force

Which produce would best increase the amount of heat energy that is actually gained by calorimeter b

The peak wavelength for the blackbody curve of a star is in the uv range. assuming the radiation from this star can reach earth, would you be able to see it?