What substance canbe scratched or get scratched by another substance?

What membranes allow some materials to pass while constraining the movement of other molecules.? If the name of a compound contains the name of metal and a nonmetal the compound is probably? Can you use Play sand in your terrarium? Does salt water affect bean plant growth? How do cells prevent mutations during DNA replication? When is water bath used in distillation? What is the atomic weight of technetium? What is a good sentence for alkali metals? Do bases lose or gain hydrogen ions? What is the molecular structure of orange juice? What is the characteristic weather conditions in an area over a long period of time? What is the overall force acting on an object? If I spit on someone could I go to jail for assault? What makes shaving cream foam? What name is given to a material which returns to its and original shape after being deformed? What is the ecological difference between algae and fungi? Earth is one of the eight what that orbits the sun? What are three elements in the same family? When you squeeze the rubber bulb of a perfume atomizer how do you change the air pressure at the top of the tube? Is an opal rough or soft?