Metallurgical Thermodynamics and Kinetics MCQ Questions and Answers

41

The weight % of nitrogen (N₂) in liquid iron can be expressed as:

A) $$K{\left( {P{N_2}} \right)^{\frac{1}{2}}}$$ B) √K . PN₂ C) $${\left( {K.P{N_2}} \right)^{\frac{1}{2}}}$$ D) K . PN₂

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Answer & Solution

Answer: Option A

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42

The ratio of fugacity of the substance to the fugacity in its standard state

A) $$a = \frac{f}{{{f^0}}}$$ B) Mixed fugacity C) activity D) Both A and C

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Answer & Solution

Answer: Option D

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43

Melting point of a metal is 1356 K. When the liquid metal is undercooled to 1256 K, the free energy change for solidification, ΔG^L-S = - 1000 J mol^-1. On the other hand, if the liquid metal is undercooled to 1200 K, the free energy change (in J mol^-1) for solidification is

A) -950 B) -1150 C) -1550 D) -1950

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Answer & Solution

Answer: Option C

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44

For a spontaneous natural process at constant temperature and pressure, the free energy of the system always

A) increases B) decreases C) remains constant D) increases to a maximum before decreasing

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Answer & Solution

Answer: Option A

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45

The rate of reaction for first order reaction

A) Rate = K B) Rate = K[A] C) Rate = K[A][B] D) Rate = K[A][B][C]

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Answer & Solution

Answer: Option B

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46

Decomposition of calcium carbonate occurs as:
CaCO₃ = CaO + CO₂ : ΔG⁰_T = 17710 - 158T J. mol^-1
What will be the decomposition temperature (in K) of CaCO₃, if the activity of CaO is 0.5 and the pressure is 3 atmospheres?

A) 142.7 B) 1120.9 C) 1424.8 D) 2549.6

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Answer & Solution

Answer: Option A

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47

Roasting of a metallic sulfide MS in pure oxygen is carried out at a particular temperature where the probable stable solid phases are M, MS, MO and MSO₄. In case the system attains equilibrium and thus satisfies phase rule, it is possible to obtain a combination of the following solid phases in the roasted product.
P. M, MS and MO
Q. M, MS, MO and MSO₄
R. MSO₄, MS and MO
S. MS and MO

A) P or Q B) P or, Q or, R C) Q or, R or, S D) P or, R or, S

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Answer & Solution

Answer: Option B

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48

G = U + PV - TS. Then which one of the following is correct?

A) $${\left( {\frac{{\partial V}}{{\partial T}}} \right)_p} = {\left( {\frac{{\partial S}}{{\partial P}}} \right)_T}$$ B) $${\left( {\frac{{\partial V}}{{\partial T}}} \right)_p} = - {\left( {\frac{{\partial S}}{{\partial P}}} \right)_T}$$ C) $${\left( {\frac{{\partial V}}{{\partial T}}} \right)_p} = {\left( {\frac{{\partial P}}{{\partial S}}} \right)_T}$$ D) $${\left( {\frac{{\partial V}}{{\partial T}}} \right)_p} = - {\left( {\frac{{\partial P}}{{\partial S}}} \right)_T}$$

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Answer & Solution

Answer: Option B

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49

In case of homogenous nucleation, the critical edge length for a cubed shaped nucleus is (Y : Energy per unit area of interface between the product and the parent phase; Δg : Gibbs free energy change per unit volume)

A) $$ - \frac{{4Y}}{{\Delta g}}$$ B) $$ - \frac{{42}}{{\Delta g}}$$ C) $$\frac{Y}{{\Delta g}}$$ D) $$ - \frac{{3Y}}{{\Delta g}}$$

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Answer & Solution

Answer: Option A

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50

When there is existence of uniform temperature throughout the system is called

A) Thermal equilibria B) Thermal nonequilibria C) Thermal instability D) None of these

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Answer & Solution

Answer: Option A

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Metallurgical Thermodynamics and Kinetics MCQ Questions and Answers | Metallurgical Engineering