2 questions in one HELP

Which statement best describes isomers? a. isomers are alcohols that have the same functional group. b. isomers have at least one carbon-carbon double bond. c. isomers have the same molecular formula but different structural properties.

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?

If c + di is a point on the circle, then | c + di |=