The total amount of energy in the universe never changes, but the amount of energy available for work at any given moment varies tremendously What best explains this change in available energy?
O A Energy can only be created through nuclear reactions
B. Energy is continually changing from one form into another
C Energy is always transferred as heat
OD Energy is always converted with 100 percent efficiency

The volumes of a sample of lead and a sample of platinum are the same: 2 cm3. the density of lead is 11.3 g/cm3 and the density of platinum is 21.5 g/cm3. which is an accurate description of their relative masses? a. the masses of the lead and platinum samples are the same. b. the mass of the lead sample is greater than the mass of the platinum sample. c. the mass of the platinum sample is greater than the mass of the lead sample.