Atomic mass iron ( Fe ) = 55.84 a.m.u
55.84 g ------------ 6.02x10²³ atoms
24.0 g ------------- ??
24.0 x ( 6.02x10²³) / 55.84
=> 2.58x10²³ atoms
Energy cannot be destroyed or created, but energy could be transformed or transferred. For example a skiier skiing from the mouth can have potential energy transferred into kinetic energy.
Standard Molar Volume is the volume occupied by one mole of any gas at STP. Remember that "STP" is Standard Temperature and Pressure. Standard temperature is 0 &176:C or 273 K. Standard pressure is 1 atmosphere or 760 mm Hg (also called "torr"). 1 mole of any gas at STP occupies 22.4 liters of volume.