GATE XE format:nat PYQs & Answers — Page 65 — Exam Papers

Questions 641–650 of 668. Imported answers require independent review unless marked reviewed.

Topic practice 668 questionsPage 65 of 67

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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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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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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The density of polyethylene crystals is 998 kg/m³ and that of totally amorphous polyethylene is 886 kg/m³. If the density of a polyethylene sample is 949 kg/m³, the crystallinity in volume fraction is ____ % (round off final answer to two digits after decimal place).

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The polydispersity index of a polymer sample containing 200 molecules each of molecular weight 10,000 gmol⁻¹, 300 molecules each of molecular weight 30,000 gmol⁻¹ and 500 molecules each of molecular weight 50,000 gmol⁻¹ is ______ (round off final answer to two digits after decimal place).

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A composite of polypropylene reinforced with 20% by volume of glass fibre is to be prepared. If the density of glass fibre is 2540 kg/m³ and polypropylene is 900 kg/m³, then the mass of glass fibre required per kg of composite is ______ g (round off answer to the nearest whole number).

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For the polycondensation of equimolar amounts of adipic acid with hexamethylene diamine, if the number average degree of polymerization is 100, then the extent of reaction is ______ %.

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The relaxation time for a rubber band at 23 °C is 60 days. If it is stressed to 2 MPa initially, then the time required before the stress relaxes to 1 MPa is ______ days (round off final answer to two digits after decimal point).

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Given T_g of polymer A is 100 °C and that of polymer B is -100 °C, then the T_g of a miscible blend of A and B containing 30 wt% of A is ______ °C (round off final answer to a single digit after decimal point).

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You have two samples of milk, one (X) with 3.8% fat and another (Y) with 0.5% fat. In order to produce a milk with 3.5% fat, 100 ml of Y should be mixed with ______ ml of X.

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