What are the main causes of convection currents in the atmosphere

The circles, or orbits, for electrons are called energy levels. each level can hold only a certain number of electrons. add electrons to each level until you can't add any more. how many electrons can each level hold?

If bacteria are much too small to see, what is one reason why can we see colonies in the petri dishes that have plenty of food to eat after only a few days?

What would happen if the tubing with the yellow band was placed in a beaker of distilled water?