What is contained in the nucleus of a comet?

Can someone list any possible solutions to air pollution ?

Computer models can scientists predict weather. some computer models can show the predicted path of hurricanes. what other events could a computer model warn us of? a) undersea earthquakes , tornadoes, and avalanches b) tornadoes c) avalanches d) undersea earthquakes

Which theory suggested that the earth was once a signle supercontient that gradually that broke up into the contients that we know today