How many more valence electrons does this atom need to fulfill the Octet Rule? (Urgent need help)

This drawing shows a human body system. what is the primary function of this body system?

Volume is a measurement of how fast particles of a substance are moving

Calcium carbonate decomposes at high temperatures to give calcium oxide and carbon dioxide as shown below. caco3(s) cao(s) + co2(g) the kp for this reaction is 1.16 at 800°c. a 5.00 l vessel containing 10.0 g of caco3(s) was evacuated to remove the air, sealed, and then heated to 800°c. ignoring the volume occupied by the solid, what will be the mass of the solid in the vessel once equilibrium is reached?