How many formula units are in one mole of each below. sodium chloride (NaCl)
lithium fluoride (LiF)
silver oxide (Ag2O)

D. most models represent a real world object in a simpler way

Heat is involved in chemical change in two ways; chemical changes either result in heat being added to or removed from an object, and chemical changes require a certain amount of heat before they can take place.

Burned piece of steel wool does not gain mass. so only d could be true.

This question is rather vague, but i will try and answers it as best i can.start by being polite, then complement on the attributes that you like about that person. be friendly to her friends. don't be mean to anybody she knows, even if you really don't like them. be yourself, don't try to impress, just be yourself and hope that she likes you.