How external and internal factors contribute in maintaining homeostasis in nature?

Check all that apply diatoms are marine algae that have a shell made of silica, what are some of the uses of the silica shell after the diatoms die? 1.the shells make up the diatomaceous earth used in filters 2.it can be used as an ingredient in abrasives 3.they are used in food products 4.the shells can be used in some insulating materials

Me the formula cacl2 represents the compound

What is the most common structure of volcanoes?