Why are there two fluoride ions in magnesium fluoride but only one fluoride ion in lithium fluoride

Which best represents the law of conservation of mass ?

The speed of sound in ice, water, and steam is shown. what best explains the speed of sound in different states of matter? sound travels fastest in ice because energy is easier to transfer when the molecules are close together. sound travels slowest in steam because the sound has to move around the gas molecules that are far apart. sound travels fastest in ice because the temperature of solids is always greater, so the heat transfers the sound energy. sound travels slowest in steam because the pressure is so great the sound cannot travel though the steam particles.

How do you tell if someone actually cares about you? and just say they do?