How would you describe a food chain to someone who never thought about that idea before

Look at the reaction below: ca(hco3)2 --> caco3 + co2 + h2o first, balance the reaction. once balanced, use dimensional analysis or another method to find out how many moles of carbon dioxide will be produced if we start with 16.5 moles of calcium bicarbonate (calcium hydrogen carbonate). = mol of co2 number needs to be reported to three significant figures.

The answer for #3 is c but i don't know why

Which function is performed by earths atmosphere? a. ultraviolet rays are prevented from reaching the ozone layer. b. earths temperature is raised and moderated by trapping in heat c. charged particles from the sun are prevented from reaching earth. d. magnetic charges from space are prevented from reaching earths surface.