HELP ASAP PLS a 35.0 g block of copper is dropped into 450 grams of water at 21.5 C. The temperature of the water changes to 22.3 C. Does the water's temperature rise or fall?

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

Which sentence about particles in matter is true? a. atoms are present in solids and liquids but not in gases. b. the particles of matter are in constant motion. c. the same kinds of atoms are found in different elements. d. when a solid changes to a liquid, the sizes of the particles change.

To prevent the presence of air, noble gases are placed over highly reactive chemicals to act as inert "blanketing" gases. a chemical engineer places a mixture of noble gases consisting of 4.37 g of he, 13.36 g of ne, and 36.65 g of kr in a piston-cylinder assembly at stp. calculate the partial pressure in torr of kr.