Samples of different materials, A and B, have the same mass, but the sample of B is higher in density. Which statement could explain why this is so? A. The particles that make up material A are more closely packed together than the particles that make up material B.
B. The sample of material B has greater volume than the sample of material A.
C. The particles that make up material B are more closely packed together than the particles that make up material A.
D. The particles that make up material A have more mass than the particles that make up material B.

Air enters a gas turbine with two stages of compression and two stages of expansion at 100 kpa and 17°c. this system uses a regenerator as well as reheating and intercooling – the intercooler returns the air to the inlet temperature. the pressure ratio across each compressor is 4 ; 300 kj/kg of heat are added to the air in each combustion chamber; and the regenerator operates perfectly while increasing the temperature of the cold air by 20°c. determine the system’s thermal efficiency. assume isentropic operations for all compressor and the turbine stages and use constant specific heats at room temperature. (0.378)