Plutonium -241 is an isotope of plutonium that is highly radioactive and is used in some nuclear reactors and many nuclear weapons . It has a half -life of 14.4 years . If 1000g of Pu - 241 is placed in storage at a weapons plant , how much will still be remaining after 28.8 years ? A. 125g
B. 250g
C. 500g
D. 1000g

The Answer is B I just did it

4r-134a enters the condenser of a residential heat pump at 800 kpa and 50°c at a rate of 0.022 kg/s and leaves at 750 kpa subcooled by 3°c. the refrigerant enters the compressor at 200 kpa superheated by 4°c determine (a) the isentropic efficiency of the compressor, (b) the rate of heat supplied to the heated room, and (c) the cop of the heat pump. also, determine (d) the cop and rate of heat supplied to the heated room if this heat pump operated on the ideal vapor-compression cycle between the pressure limits of 200 and 800 kpa. (0.757, 4.37 kw, 5.12, 6.18, 3.91 kw)