All these problems you just posted are related. To answer them you must remember: a) The MOLE is a number, How many things are in a mole? Look up AVOGADRO'S NUMBER in your textbook. b) You can't count moles , you must WEIGH them. What is the weight of one mole of something? It concerns the material's ATOMIC, MOLECULAR OR FORMULA WEIGHT. Then all you need is some elementary math skills. Try the problems you have posted and we will be happy to help you through any difficulties.