GATE MT topic:laws-thermodynamics PYQs & Answers — Page 6

Questions 51–60 of 69. Imported answers require independent review unless marked reviewed.

The partial pressure of zinc (in torr, rounded off to two decimal places) in equilibrium with liquid lead containing 0.03 mole % zinc at 900 K is _____________.

Given: Vapour pressure of pure zinc (

) at 900 K is 0.027 atm. Henry’s law coefficient (

) for zinc at infinite dilute solution in lead on Raoultian scale is 8.55.

1 torr = 1.316 × 10⁻³ atm.

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Equilibrium concentration of dissolved nitrogen (in wt.%, rounded off to three decimal places) in pure liquid iron, exposed to atmospheric air at 1873 K, is ________.

Given: Sieverts’ law constant as a function of temperature (

; in Kelvin) is

where

has the dimension of

. Assume

, where

is the activity of nitrogen with respect to 1 wt.% Henrian standard state.

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During decarburization in a steel bath at 1550 °C, the compositions of dissolved C (wt.%C) and dissolved O (wt.%O) follow the relation: (wt.%C)(wt.%O) = K When the partial pressure of CO (

) is 1 atm, K = 0.002. If

atm, what is the value of K, at the same temperature? Note: Assume Henry’s law is applicable.

Your answerChoose one option.

0.06

0.002

0.02

0.0002

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At equilibrium, the maximum number of phases in a three-component system at CONSTANT PRESSURE is:

Your answerChoose one option.

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For a single phase system with K components, the exact differential of Gibbs free energy is given as:

Which one of the following can be derived from the above expression as a Maxwell’s relation?

Your answerChoose one option.

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In the A-rich end of the A-B binary eutectic phase diagram (shown below), the solid and liquidus are straight lines.

Diagram for Metallurgical Engineering question 22

The freezing range of the alloy with 16% B is ________ (in °C to one decimal place)

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The molar free energy (J mol

) of a liquid solution of a binary A-B alloy as a function of temperature (

) and composition (

, the mole fraction of B) is given by:

where

and

are the molar free energies of pure liquid A and pure liquid B. What is the excess molar free energy,

, for an alloy with

Given: Gas constant R = 8.314 J K

mol

Your answerChoose one option.

100 J mol

−200 J mol

463 J mol

−563 J mol

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If 2 moles of Au and 3 moles of Ag are mixed to form a single-phase ideal solid solution, the total entropy of mixing is ______ (on J K

to one decimal place) Given: Gas constant R = 8.314 J K

mol

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At a temperature of 710 K, the vapour pressure of pure liquid Zn is given by:

. The Raoultian activity coefficient (

) of Zn in Zn-Cd alloy liquid at 710 K is approximated by:

. The ratio

for a liquid alloy with

is ______ (to two decimal places).

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For the reaction: 4Ag(s, pure) + O

(g) → 2Ag

O(s, pure), the standard enthalpy change,

, and the standard entropy change,

, in the temperature range from 298 K to 500 K. The temperature above which Ag

O decomposes in an atmosphere containing oxygen at a partial pressure

is ______ (in K to one decimal place). Given: Gas constant R = 8.314 J K

mol

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GATE MT topic:laws-thermodynamics PYQs

Question 40

Question 43

Question 6

Question 11

Question 12

Question 22

Question 26

Question 48

Question 50

Question 51