The lattice energy of caf2 is the energy change for which one, if any, of the following processes? a) caf2(g) ⟶ caf2(s) b) ca(g) + 2f(g) ⟶ caf2(s) c) ca2+(s) + 2f–(g) ⟶ caf2(g) d) no correct answer choice listed e) caf2(aq) ⟶ caf2(s)

What is the force of attraction between the particles in a salt crystal

Determine the wavelength of the light absorbed when an electron in a hydrogen atom makes a transition from an orbital in the n=3 level to an orbital in the n=7 level.

Agroup of students is studying convection current. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other is in an area with warm air. after 10 minutes, the balloon are released from a height of 1 meter. which of the following to the students most likely observe? a) the warm balloon expands and rises. the cold balloon shrinks and sinks b) the balloon both rise. the cold balloon is larger than the warm balloon c) the cold balloon expands and rises. the warm balloon shrinks and sinks d) the balloon rise at the same rate. both balloons are the same size