Pennies used to be made of copper and zinc and had a mass of of 3.1 g. today pennies are made of copper-platted zinc and have a mass of 2.5 g. a new penny's mass is what percent of an old penny's mass?

You are performing an experiment in a lab to attempt a new method of producing pure elements from compounds. the only problem is that you do not know what element will form. by your previous calculations you know that you will have 6.3 moles of product. when it is complete, you weigh it and determine you have 604.4 grams. what element have you produced?

When an object falls through the air and encounters air resistance its overall speed will be than if it had not encountered air resistance? (one word answer)

Which other elements contain the same number of outer electrons as sodium