Why is the formula of calcium nitrate "ca(no3)2" and not "cachno6" or anything else?

What are several ways to reduce the effect of friction

Name 3 types of energy you see being used as you look around a classroom

How does a sample of helium at 15 degree celsius compare to a sample of helium at 215 k? a) the helium at 15 degrees celsius has a higher average kinetic energy that the sample at 215 k. b) the helium at 15 degrees celsius has lower nuclear energy that the sample at 215 k. c) the helium at 15 degrees celsius has slower- moving atoms that the sample at 215 k. d) the helium at 15 degrees celsius has smaller atoms than the sample at 215 k.