Sodium (Na) and chlorine (CI) combine to form a __ of salt (NaCI)
A. Mixture
B. Molecule

Which sentence about particles in matter is true? a. atoms are present in solids and liquids but not in gases. b. the particles of matter are in constant motion. c. the same kinds of atoms are found in different elements. d. when a solid changes to a liquid, the sizes of the particles change.

The twister and runaway train are two coasters at the same amusement park. both coasters start at the same height. the coaster for the twister is twice the mass of the coaster for the runaway train. which roller coaster has greater gravitational potential energy at the start of the ride?

Elements in group 2 are all called alkaline earth metals. what is most similar about the alkaline earth metals?