1. All of the following are true regarding solids except for: A) Molecules are tightly packed in a solid.
B) Molecules vibrate at a slow speed, in a fixed position
C) Molecules move quickly and freely past one another in a solid.
D) A solid has a definite shape and structure,​

Ihave no idea how to solve these. plus there's another question that is 2) a 10 kilogram meteorite is collected in space and brought back to earth. it is composed of 1.25 kg of uranium-238 and 8.75 kg of lead-206. how many u-238 half lives have passed? what is the approximate age of the meteorite?