Questions 1691–1700 of 1772. Imported answers require independent review unless marked reviewed.

Topic practice 1772 questionsPage 170 of 178

Question 94

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An ideal gas having a mass of 0.5 kg is initially at 300 kPa, 80°C and occupies a volume of 0.14 m³. The gas undergoes an adiabatic process, where 50 kJ of work is transferred to the gas. The pressure and volume at the final state are 300 kPa and 0.20 m³. The change in the entropy of the gas in J/K is
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Question 95

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The van der Waals equation of state is given as,

where p in bar, v in m³/kmol and T is in K. For air, the constants, a and b, are 1.368 bar.(m³/kmol)² and 0.0367 m³/kmol, respectively. Air is contained in a system at 160 K and 0.08 m³/kmol. If p₁ is the pressure calculated using ideal gas equation of state and p₂ is pressure calculated using van der Waals equation of state, then p₁/p₂ is equal to
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Question 96

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The values of specific volume of H₂O at 100°C for saturated liquid and saturated vapor states are 0.00104 m³/kg and 1.673 m³/kg, respectively. The slope of saturation pressure versus temperature curve, i.e.,

is 3570 Pa/K. The change in enthalpy in kJ/kg between the two saturation states is _________.

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Question 97

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In a steam power plant, steam is first expanded isentropically in a turbine from an initial condition of 100 bar and 500 °C to a pressure of 40 bar. Then the steam is reheated up to 500 °C at constant pressure. The steam is then expanded isentropically in another turbine up to a condenser pressure 0.01 bar. For steam, at 100 bar, 500°C: h = 3373.7 kJ/kg, s = 6.596 kJ/kg.K; at 40 bar, 500°C: h = 345.3 kJ/kg, s = 7.091 kJ/kg.K and at 0.01 bar: h_f = 29.3 kJ/kg, h_g = 2514.2 kJ/kg, s_f = 0.1059 kJ/kg.K, s_g = 8.9756 kJ/kg.K. The dryness fraction at the condenser inlet (up to 2 decimal places) is _________.

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Question 98

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Air contains by volume 79% N₂ (molecular weight = 28 kg/kmol) and 21% O₂ (molecular weight = 32 kg/kmol). A stream of air flows at 32°C, 1 bar, at a rate of 2 m³/s and is mixed with another stream of O₂ flowing at 0.4 kg/s. The molecular weight of the mixture (up to 2 decimal places) is _________.

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Question 99

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Moist air enters a duct at a rate of 3 kg/s at 10°C, 80% relative humidity. The air is heated as it flows through the duct and exits at 30°C. No moisture is added or removed and the pressure of air in the duct is constant at 1 bar. The saturation vapor pressure (p_g) of H₂O at 10°C is 0.01228 bar. Specific enthalpy values of dry air at inlet and outlet of the duct are respectively 283.1 kJ/kg and 303.2 kJ/kg. The corresponding specific enthalpy values for water vapor are 2519.8 kJ/kg and 2556.3 kJ/kg. For steady state operation the amount of heat added to the moist air in kW (up to 2 decimal places) is _________.

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Question 100

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Poly(ethylene terephthalate) is synthesized from
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Question 101

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Poly(vinyl chloride) has a higher T_g than polypropylene due to the presence of
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Question 102

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The filler which would impart electrical conductivity to a polymer is
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Question 103

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Which one of the following catalysts is used to prepare ‘isotactic’ polypropylene?
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