Which has been the primary source of energy in the most recent century? O wood and coal
O wood and nuclear
O petroleum, natural gas, and coal
hydroelectric and other renewables

What is the specific heat of a substance that absorbs 2.5×10^3 joules of heat when a sample of 1.0 ×10^4g of the substance increases in temperature from 10°c to 70°c?

Which statement correctly describes metallic bonds? a. they form when certain atoms lose electrons and other atoms gain electrons. b. they involve an attraction between anions and cations. they always involvpoth a metal and a nonmetal. d. they can only form between atoms of the same element. e. they form because electrons can move freely between atoms.

11. phosphorus-32 is radioactive and has a half life of 14 days. how much of a 124 mg sample of phosphorus-32 is present after 56 days? a) 7.75 mg b) 15.5 mg c) 31.0 mg d) 62.0 mg