What is a system called when neither energy nor matter is exchanged between the system and the surroundings?
closed system
free energy
isolated system
open system

In 2002, the rare earth elements mine in mountain pass, california was closed because

Marcel just purchased 1.69 grams of iron fillings in order to make living putty for his 6 year old niece. how many moles of iron are made in his sample?

13. a covalent bond between two atoms is likely to be polar if: a. one of the atoms is much more electronegative than the other. b. the two atoms are equally electronegative. c. the two atoms are of the same element. d. the bond is part of a tetrahedrally shaped molecule. e. one atom is an anion.