Cementite (Fe$_3$C) crystal structure is
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- Orthorhombic
- BCT
- HCP
- FCC
The Correct Option is A
Solution and Explanation
Top Questions on Thermodynamics
- A piston-cylinder assembly having 250 mm diameter contains 0.01 kg of water vapor at 1 MPa and 200°C. The specific volume of the vapor is 0.020602 m\(^3\)/kg. The system expands as per the relation \( p v^n = {constant} \), where \( p \) is pressure and \( v \) is the specific volume. The expansion of water vapor displaces the piston by 50 mm. If the final pressure is 0.35 MPa, the value of the exponent \( n \) is ........ (rounded off to two decimal places).
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A stream of superheated steam (2 MPa, 300°C) mixes with another stream of superheated steam (2 MPa, 400°C) through a steady-state adiabatic process. The flow rates of the streams are 3 kg/min and 2 kg/min, respectively. This mixture then expands in an adiabatic nozzle to a saturated mixture with quality of 0.77 and 1 kPa. Neglect the velocity at the nozzle entrance and the change in potential energies. The velocity at the nozzle exit (in m/s) is ......... (rounded off to two decimal places).
Use the following data:
At 2 MPa, 300 °C: Specific enthalpy of superheated steam = 3024.2 kJ/kg
At 2 MPa, 400 °C: Specific enthalpy of superheated steam = 3248.4 kJ/kg
At 1 kPa: Specific enthalpy of saturated water = 29.3 kJ/kg
At 1 kPa: Specific enthalpy of saturated vapour = 2513.7 kJ/kg
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- Consider a gas obeying the relation \( P(v - b) = RT \), where \( b \) and \( R \) are constants. Which of the following statement(s) is/are CORRECT about the specific heat capacity at constant pressure?
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- Thermodynamics
- A rigid tank of 300 litre capacity contains 3 kg of oxygen (molar mass = 32 kg/kmol) at 25°C. If oxygen behaves as an ideal gas, the pressure (in kPa) inside the tank is ......... (rounded off to two decimal places).
Use: Universal gas constant \( R_u = 8.314 \, {kJ/kmol-K} \)
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- Thermodynamics
- If \( \gamma \) refers to the ratio of specific heats, the air-standard efficiency of an Otto cycle is
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