How many moles of mgs2o3 are in 195 g of the compound?

Need on both questionswill markbr />

Apump contains 0.5 l of air at 203 kpa.you draw back on the piston of the pump, expanding the volume until the pressure reads 50.8 kpa. what is the new volume of the air pump

What does the symbol (–hfus) indicate in a phase change?