How many valence electrons does helium need to have a filled outermost energy level?

What does earth’s rotation on its axis cause? the tides night and day passing of years phases of the moon

Adilute aqueous potassium nitrate solution is

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?