Metallurgical Thermodynamics And Kinetics MCQ

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• For any given partial pressure of CO over liquid steel at a constant temperature, the activities of carbon and oxygen in the metal are related to a constant β as
  ক

  a_c . a₀ = β

  খ

  $$\frac{{{a_c}}}{{{a_0}}} = \beta $$

  গ

  a_c = β . a²₀

  ঘ

  a²_c = β.a⁰
• The effect of temperature and pressure on chemical equilibrium can be predicted by
  ক

  Vant Hoff equation

  খ

  Le-Chatlier's principle

  গ

  Law of mass action

  ঘ

  Clausius-Clayperon equation
• If a multicomponent heterogeneous system at thermodynamic equilibrium, identify the option that need not be true.
  ক

  Uniform pressure

  খ

  Uniform temperature

  গ

  Uniform chemical potential

  ঘ

  Uniform composition
• In BOF, desiliconisation is a first order reaction. So, the silicon content of the metal decreases
  ক

  linearly with time

  খ

  exponentially with time

  গ

  logarithmically with time

  ঘ

  in proportion to the square root of the time
• In which of the following reactions, application of vaccum will help?
  ক

  Number of gas molecules in the product side is more than that on the reactant side

  খ

  Number of gas molecules in the reactant side of more than that on the product side

  গ

  Number of gas molecules are the same on both the reactant and product side

  ঘ

  None of the above
• Consider the equilibrium A(g) + B(g) = AB(g). When the partial pressure of A is 10^-2 atm; the partial pressure of B is 10^-3 atm and the partial pressure of AB is 1 atm; the equilibrium constant K is
  ক

  10 atm^-1

  খ

  10⁵ atm^-1

  গ

  10 (dimensionless)

  ঘ

  10⁵ (dimensionless)
• For the following reactions, the standard free energy change is given at 1773 K as follows:<br>$$\frac{2}{3}$$ Cr₂O₂(s) = $$\frac{4}{3}$$ Cr(s) + O₂(g)<br>ΔG° = 447800 J<br>2H₂(g) + O₂(g) = 2H₂O(g)<br>ΔG° = - 297000 J<br>If chromium oxide powder has to be reduced by hydrogen in a fludised bed, the minimum $$\frac{{P{H_2}}}{{P{H_0}}}$$ ratio that has to be maintained at the exit of the reactor is
  ক

  8.5

  খ

  10.6

  গ

  100.2

  ঘ

  166.5
• Configurational entropy due to ideal mixing in a binary A - B system is expressed as:<br>ΔS_mix = - R(X_A In X_A + X_B In X_B),<br>where X_A and X_B are mole fractions of A and B respectively.<br>ΔS_mix is maximum at X_A = . . . . . . . .
  ক

  0.1

  খ

  0.2

  গ

  0.5

  ঘ

  0.9
• If a solid is compressed adiabatically in its elastic range, its
  ক

  internal energy remains constant

  খ

  enthalpy remains constant

  গ

  entropy remains constant

  ঘ

  temperature remains constant
• The portion or quantity of the universe/matter that is selected for study are separated from surrounding is
  ক

  system

  খ

  component

  গ

  phase

  ঘ

  degree of freedom
• For a binary solution A - B, the α-function is given by $$\alpha = \frac{{\exp \left( x \right) - 1}}{X}$$     Where, X is the mole fraction of component A. The limiting value of a when X approaches zero, is
  ক

  1

  খ

  infinity

  গ

  indeterminate

  ঘ

  Zero
• The concentration of a dissolved gas is directly proportional to the partial pressure of that gas
  ক

  Raouls's law

  খ

  Kirchoff's law

  গ

  Dalton's law

  ঘ

  Henry's law
• The activation energy for a reaction is 100 kJ/mole. The approximate increase in temperature required for doubling the rate of reaction from that at 25°C, is . . . . . . . . °C.
  ক

  5

  খ

  10

  গ

  15

  ঘ

  20
• Consider the reaction:<br>Fe₃O₄ (solid, pure) + CO (gas, 1 atm) → 3FeO (solid, pure) + CO₂ (gas, 1 atm)<br>For this reaction, ΔG₁₂₀₀ = -8000 joules per mole of CO and R = 8.314 J mol^-1 K^-1.<br>The equilibrium ratio, $$\frac{{pc{o_2}}}{{pco}}$$ reaction at 1200 K and 1 atm is . . . . . . . .
  ক

  0.8

  খ

  1.8

  গ

  2.2

  ঘ

  4.6
• For the reaction, A = X + Y, the respective concentrations are C_A, C_X and C_Y. The forward reaction rate constant is kf and the backward reaction rate constant is kb. Choose the correct statement from the following:<br>P. At equilibrium, kf C_A &gt; k_B CxCy<br>Q. If the reaction is irreversible than, kb C_XC_Y = 0<br>R. The backward reaction rate will essentially be first order, if the forward reaction rate is first order.<br>S. Activation energy for the first order forward reaction will be independent of temperature.
  ক

  P, Q

  খ

  Q, R

  গ

  R, S

  ঘ

  Q, S
• The heat capacity of diatomic ideal gas
  ক

  $${C_V} = \frac{5}{2}R$$

  খ

  $${C_P} = \frac{7}{2}R$$

  গ

  Both A and B

  ঘ

  None of these
• AG_(s) = Ag_(t), T = 1234K; ?H = 11300 J.mol^-1 ?C_P = Cp_(t) - Cp_(s) = 0<br>When one mole of super cooled liquid silver freezes at an ambient temperature of 1000 K, the total entropy change of the system (Ag) and the surroundings is . . . . . . . . J.K^-1.
  ক

  11.3

  খ

  9.16

  গ

  0

  ঘ

  2.14
• FeO(s) + CO(g) = Fe(s) + CO₂(g); K = 0.435 at 1173 K. At equilibrium, what will be the number of moles of CO gas required to reduce one mole of FeO at 1173K?
  ক

  1

  খ

  1.3

  গ

  2.3

  ঘ

  3.3
• Which of the following- properties is Intensive?
  ক

  Volume

  খ

  Gibbs free energy

  গ

  Chemical potential

  ঘ

  Entropy
• For a first order chemical reaction the concentration of the reactant decreases
  ক

  linearly with time

  খ

  exponentally with time

  গ

  logarithmically with time

  ঘ

  inversely with time
• As the concentration of point defects in a crystal increases, its configurational entropy
  ক

  does not change

  খ

  decreases

  গ

  increases

  ঘ

  initially increases and then decreases
• The limiting condition for the appearance of the miscibility gap in a binary solution is<br>Where, G is the Gibbs free energy and X is the mole fraction of component Z.
  ক

  $$\left( {\frac{{{\partial ^2}G}}{{\partial {X^2}}}} \right) = 0$$

  খ

  $$\left( {\frac{{{\partial ^3}G}}{{\partial {X^3}}}} \right) = 0$$

  গ

  $$\left( {\frac{{{\partial ^2}G}}{{\partial {X^2}}}} \right) + \left( {\frac{{{\partial ^3}G}}{{\partial {X_3}}}} \right) = 0$$

  ঘ

  $$\left( {\frac{{{\partial ^2}G}}{{\partial {X^2}}}} \right) - \left( {\frac{{{\partial ^3}G}}{{\partial {X^3}}}} \right) = 0$$
• The expression for gas law is
  ক

  PV = nRT

  খ

  PT = nVR

  গ

  VT = nPR

  ঘ

  None of these
• The activity co-efficient of the solute in a dilute solution
  ক

  decreases with increase of concentration of the solute

  খ

  increases with increase of concentration of the solute

  গ

  remains constant

  ঘ

  is unity at infinite dilution
• The units of the rate constant for it second order reaction are
  ক

  Sec^-1 . moles

  খ

  moles⁺¹ . sec^-1

  গ

  moles^-1 . sec^-1

  ঘ

  moles¹ . sec¹
• The vapour pressure of a solid M varies with temperature T in K, as<br>In p(atm) = $$frac{{ - 33,200}}{T}$$ - 0.85 In T + 21.46<br>The vapour pressure of liquid M varies with temperature T, in K, as<br>In p (atm) $$frac{{ - 33,200}}{T}$$ = 0.85 In T + 20.31<br>The temperature of the triple point of M, in K is
  ক

  57

  খ

  96

  গ

  579

  ঘ

  957
• If a binary system exihibits a miscibility gap in the solid state, then the enthalpy of mixing in the solid state, ΔH^mix should necessarily be
  ক

  zero

  খ

  positive

  গ

  negative

  ঘ

  equal to the free energy of mixing
• The sequence of processes which return back to its initial point is called
  ক

  adiabatic process

  খ

  isothermal process

  গ

  cyclic process

  ঘ

  isobaric process
• Integral enthalpy of mixing (in J/mol) of liquid (Cu, Zn) solution can be approximated by ΔH_m^mix = - 19250 X_CuX_Zn<br>The corresponding partial molar enthalpy of mixing (in J/mol) for Cu is
  ক

  19250x²_zn

  খ

  - 19250x²cu

  গ

  38500x_zn - 19250x²_zn - 19250

  ঘ

  - 19250 x²_zn
• The first law of thermodynamics can be stated as:
  ক

  dE = δQ - δW

  খ

  dQ = dE - δW

  গ

  δW = dQ + dE

  ঘ

  dW = δQ - δE