Sound CANNOT be heard in what? 1: Wooden door
2: a vacuum
3: the ocean
4: a glass jug

Which element forms an ionic bond with flourine? 1) fluorine 2) carbon 3) potassium 4) oxygen

6what is the importance of water on earth? a) it keeps the top layer of the geosphere cool b) it allows life to exist c) it provides ice at the poles d) it creates earth's blue color from space

An atom of lithium-7 has an equal number of(1) electrons and neutrons(2) electrons and protons(3) positrons and neutrons(4) positrons and protons