Is it a physical or chemical change when a candle is lit

Calculate the number of molecules present in 0.750 mol of mgo.

In a covalent bond, two atoms are held together by the attraction between . the number of covalent bonds that an atom can form depends on the number of in the atom.

You have 125 g of a certain seasoning and are told that it contains 70.0 g of salt. what is the peroentage of salt by mass in this seasoning?