(1). A system contains water at 4.0 MPa and 275 °C. The phase of water is:
(A) Liquid only
(B) Liquid-vapor mixture
(C) Vapor only
(D) Solid only
(E) None of the above
(2). A system contains water at 4.0 MPa and 245 °C. The phase of water:
(A) Liquid only
(B) Liquid-vapor mixture
(C) Vapor only
(D) Solid only
(E) None of the above
(3). A system contains Refrigerant R-134a with the specific volume of 0.02 m^3/kg at 0.5 MPa. The phase of R-134a is:
(A) Liquid only
(B) Liquid-vapor mixture
(C) Vapor only
(D) Solid only
(E) None of the above
(4). At a pressure of 4 MPa, the temperature at which liquid water boils is:
(A) 29.0 °C
(B) 100.0 °C
(C) 143.6 °C
(D) 250.4 °C
(E) None of the above
(5). Which one is valid among the following statements about the quality, a property of pure substance?
(A) The higher the quality, the lower the percentage of vapor.
(B) The higher the quality, the better the pure substance.
(C) The quality of superheated vapor is greater than 1.
(D) The value of the quality (x) always is 0 ? x ? 1.
(E) Compressed liquid always has a quality.2
(6). Airis contained in a room with a dimension of 4 m × 5 m × 3 m at 100 kPa and 25 degree C, the mass of air in this room is closest to
(A) 35.08 kg
(B) 70.15 kg
(C) 140.30 kg
(D) 836.24 kg
(E) None of the above
(7). Which one is valid among the following statements about an ideal gas?
(A) The vapor in a liquid-vapor mixture of water is always considered as an ideal gas.
(B) An ideal gas is an imaginary substance that has high intermolecular forces and each gas molecule occupies a relative large volume.
(C) An ideal gas is an imaginary substance that is close to the real gas with very high density.
(D) The Pv=RT equation closely approximates the P-v-T behavior of the real gases at high pressure and low temperature.
(E) The Pv=RT equation closely approximates the P-v-T behavior of the low-density real gases at low pressure and high temperature.
(8). A system contains Refrigerant R-134a with the specific enthalpy of 275 kJ/kg at 600 kPa. The phase of R-134a is:
(A) Liquid only
(B) Liquid-vapor mixture
(C) Vapor only
(D) Solid only
(E) None of the above