What is the net ionic charge of a calcium ion?

Ca generally loses two electrons from its outer shell to form a Ca2+ ion.

in chemistry, adhesion and cohesion are attractive forces that exist between molecules. they hold the molecules together from each other. they are different in that adhesive force exists between molecules of different substance while cohesive force happens between molecules of same substance.

adhesion between water and glass causes water molecules at the edge of water and glass interface to climb up the wall in a narrow glass tube. this is called capillary action. cohesion is what gives glass its shape and causes water to form a droplet.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.