stellalisy/MaScQA · Datasets at Hugging Face

qid stringlengths 11 16	q_type stringclasses 4 values	correct_answer stringlengths 1 30	topic stringclasses 14 values	question stringlengths 44 799
G-XEC-2017-20	NUM	1.35 to 1.37	Electrical	Give: Charge of an electron: 1.6* $10^(-19)$C. Copper is an FCC metal with lattice paramenter of 3.62 Å. Hall effect measurement shows electron mobility to be 3.2 * $10^(-3)m^(2)V^(-1)s^(-1)$. Electrical resistivity of copper is 1.7* $10^(-8)$ Ωm. The average number of free electrons per atom in copper is ?
G-XEC-2017-21	MCQS-NUM	C	Atomic structure	In an ionic solid the cation and the anion have ionic radii as 0.8 Å and 1.6 Å respectively. The maximum coordination number of the cation in the structure will be (A) 3 (B) 4 (C) 6 (D) 8
G-XEC-2017-22	MCQS	A	Magnetism	Which of the following statement(s) is/are true regarding susceptibility of a material (i) Magnetic susceptibility is positive for a diamagnetic material (ii) Magnetic susceptibility is negative for a diamagnetic material (iii) Magnetic susceptibility is negative for an antiferromagnetic material (iv) Magnetic susceptibility is positive for a paramagnetic material (A) (ii) and (iv) (B) (i) and (iii) (C) (ii) and (iii) (D) (i) and (iv)
G-XEC-2018-1	MCQS	C	Mechanical	The stress ratio for a completely reversed cyclic loading during a fatigue test is (A) 0 (B) 1 (C) -1 (D) -1/2
G-XEC-2018-2	MCQS	A	Atomic structure	Minimum symmetry that a cubic crystal must possess is (A) four 3-fold rotation axes. (B) three 4-fold rotation axes. (C) three orthogonal mirror planes. (D) centre of symmetry.
G-XEC-2018-3	MCQS	B	Magnetism	If a material is repelled in an external magnetic field then it is (A) Ferromagnetic (B) Diamagnetic (C) Paramagnetic (D) Antiferromagnetic
G-XEC-2018-4	MCQS	C	Thermodynamics	An electron makes a transition from the valence band to the conduction band in an indirect band gap semiconductor. Which one of the following is true? (A) Energy of the electron decreases. (B) A photon is emitted in the process. (C) A phonon is annihilated in the process. (D) A photon is created in the process.
G-XEC-2018-5	MCQS	A	Atomic structure	Which one of the following is the characteristic of a screw dislocation? (A) Dislocation line and Burgers vector are parallel. (B) Direction of motion of dislocation is parallel to the Burgers vector. (C) Atomic displacement due to the movement of the dislocation is in the direction of the motion of the dislocation line. (D) It has a unique slip plane.
G-XEC-2018-6	MCQS-NUM	D	Atomic structure	The number of vibrational degrees of freedom for a non-linear triatomic molecule are (A) 9 (B) 6 (C) 4 (D) 3
G-XEC-2018-10	MATCH	B	Phase transition	Match the invariant reactions in Column I with the names in Column II (L is liquid phase, and α , β, γ are solid phases). All reactions proceed to the right on cooling. Column I : [(P) 𝐿 ⇄ 𝛼 + 𝛽, (Q) 𝐿 + 𝛼 ⇄ 𝛽, (R) 𝛾 ⇄ 𝛼 + 𝛽, (S) 𝛼 + 𝛽 ⇄ 𝛾] Column II: [(1) Monotectic, (2) Peritectoid, (3) Peritectic, (4) Eutectoid, (5) Eutectic] Options: (A) P-5, Q-1, R-4, S-3 (B) P-5, Q-3, R-4, S-2 (C) P-5, Q-1, R-2, S-4 (D) P-2, Q-1, R-4, S-5
G-XEC-2018-11	MCQS-NUM	A	Electrical	Consider the following anodic (oxidation) reaction in an acidic solution: 𝑀𝑔 ⟶ $𝑀𝑔^(+2)$ + $2𝑒^(-)$. If 48250 Coulomb charge is produced during this anodic reaction then the amount of Mg (in g) dissolved into the solution is (Given: Faraday Constant = 96500 C/mole of electrons, Atomic weight of Mg = 24) (A) 6 (B) 12 (C) 24 (D) 48
G-XEC-2018-12	MCQS-NUM	B	Electrical	An intrinsic semiconductor has conduction electron concentration, n = $10^(12)$ $cm^(-3)$. The mobility of both electrons and holes are identical = 4 * $10^4$ $cm^2$ $V^(-1)$ $s^(-1)$. If a voltage of 100 V is applied on two parallel end faces of the cube (edge length 1 cm) through Ohmic contacts, the current through the cube would be (in mA) (Given: charge of electron = 1.6 * $10^(-19)$ C) (A) 640 (B) 1280 (C) 6400 (D) 12800
G-XEC-2018-13	NUM	430 to 500	Mechanical	An infinite plate with a through-thickness crack of length 2 mm is subjected to a tensile stress (as shown in the figure). Assuming the plate to be linear elastic, the fracture stress in MPa (round off to the nearest whole number). (Given: Fracture toughness, $K_(1C)$ = 25 MPa √𝑚)
G-XEC-2018-15	NUM	2.60 to 2.70	Material Applications	(Given: Density of water = 1.00 g $cm^(-3)$). A sintered sample was weighed in air and water using an analytical balance. The mass of the sample in air is 2.67 g and its apparent mass in water is 1.67 g. Calculate the density of the sample in g $cm^(-3)$ (give answer up to 2 decimal places)
G-XEC-2018-18	NUM	132 to 132	Thermodynamics	When 3 identical non-interacting spin ½ particles are put in an infinite potential well, the ground state energy of the system is 18 meV. If instead, seven particles are put inside the potential well, the new ground state energy in meV is?
G-XEC-2018-22	NUM	1420 to 1480	Thermodynamics	Given: Activation energy Q = 148 kJ $mol^(-1)$, Gas constant, R = 8.314 J $mol^(-1)$ $K^(-1)$. Mild steel is carburized at 1300 K for 1 hour to obtain a certain case depth. Keeping the time as 1 hour, the case depth can be doubled by increasing the temperature to what temperature(in K)? (round off to the nearest whole number)
G-XEC-2019-1	MCQS	B	Miscellaneous	On decreasing the objective aperture size in an optical microscope (A) the spherical aberration increases (B) the depth of field increases (C) the diffraction-limited resolution increases (D) the astigmatism increases
G-XEC-2019-3	MCQS	A	Atomic structure	In NaCl, the substitution of a $Na^(+1)$ ion by a $Ca^(2+)$ ion would most probably lead to (A) the formation of a $Na^(+1)$ vacancy (B) the creation of a Cl‾ interstitial (C) the formation of a Cl‾ vacancy (D) the formation of a $Na^(+1)$ and Cl‾ vacancy pair
G-XEC-2019-4	MCQS	A	Mechanical	Which one of the following is time-independent? (A) Elastic deformation (B) Anelastic deformation (C) Viscoelastic deformation (D) Creep deformation
G-XEC-2019-5	MCQS-NUM	B	Transport phenomena	(Given: Diffusion coefficients of copper in aluminium at 400 °C and 500 °C are 5$10^(-14)m^(2)s^(-1)$ and 6$10^(-13)m^(2)s^(-1)$, respectively). Copper is diffused into aluminium at 400 °C for 100 hours to obtain a certain concentration at a given depth. In another experiment conducted at 500 °C, to achieve the same concentration of copper at the same depth, the time required in hours is (A) 7.33 (B) 8.33 (C) 9.33 (D) 10.33
G-XEC-2019-6	MCQS-NUM	B	Material manufacturing	(Given: atomic weight C = 12, Fe = 56). If carbon (C) in iron (Fe) is 6 percent by weight, then its atomic percent is approximately (A) 13 (B) 23 (C) 30 (D) 50
G-XEC-2019-7	MCQS	C	Thermodynamics	GaAs has advantage over silicon when used in intergrated circuits at low power because it has (A) larger band gap (B) more than one element (C) higher electron mobility (D) higher hole mobility
G-XEC-2019-8	MCQS	D	Material characterization	Glass transition temperature of a polymer can be determined by (A) Thermo-gravimetric analysis (B) Raman spectroscopy (C) NMR spectroscopy (D) Differential scanning calorimetry
G-XEC-2019-9	MCQS-NUM	B	Thermodynamics	(Given: energy gap of Ge = 0.67 eV, Planck’s constant h = 6.63 * $10^(-34)$ J s, velocity of light c = 3 * $10^(8)ms^(-1)$ and 1 eV = 1.6*$10^(-19)$ J ). The maximum wavelength of radiation to which Germanium (Ge) is opaque will be (A) 0.8 μm (B) 1.8 μm (C) 2.8 μm (D) 4.8 μm
G-XEC-2019-10	MCQS	B	Atomic structure	(Given: atomic weight of H = 1, C = 12, F = 19 and Cl = 35.5). An alternating copolymer has number-averaged molecular weight of $10^(5)gmol^(-1)$ and degree of polymerization of 2210. If one of the repeat units is ethylene, the other one is (A) $−CH_2−CH(CH_3)−$ (B) $−CH_2−CHCl−$ (C) $−CF_2−CF_2−$ (D) $−CH_2−CH(C_6H_5)−$
G-XEC-2019-11	MATCH	B	Material manufacturing	Match the sintering processes in column I with the most suitable products in column II. Coloumn I: [(P) Solid state sintering, (Q) Liquid phase sintering, (R) Spark plasma sintering, (S) Laser sintering] Coloumn II: [(1) Carbon nanotube products, (2) Mixture of Cu and Zn powder products, (3) Iron powder products, (4) 3D printed products] Options: (A) P-4; Q-1; R-2; S-3 (B) P-3; Q-2; R-1; S-4 (C) P-3; Q-2; R-4; S-1 (D) P-2; Q-3; R-1; S-4
G-XEC-2019-12	MCQS	B	Material manufacturing	Which one of the following conditions will NOT favour the separation of impurities in zone refining process? (A) Increase in the gap between solidus and liquidus lines (B) Increase in the solubility of impurities in solid as compared to that in liquid phase (C) Agitation of melt (D) Low cooling rate of melt
G-XEC-2019-15	NUM	0.28 to 0.32	Thermodynamics	(Given: Constants A = 6* $10^(-20)$ J $nm^3$, B = 2.1 * $10^(-22)$ J $nm^(7)$). The potential energy, U(r), of a pair of atoms spaced at a distance r in a solid is given by U(𝑟)= −(𝐴/$𝑟^3$) + (𝐵/$𝑟^7$) . The equilibrium distance(in nm) between the atom pair is? (round off to 2 decimal places)
G-XEC-2019-18	NUM	9.2 to 9.6	Thermodynamics	(Given: Planck’s constant h = 6.63 * $10^(-34)$ J s, 1ev = 1.6*$10^(-19)$ J, electron mass = 9.11×$10^(-31)$ kg ). The zero point energy(in ev) of an electron in a box of 0.2 nm width is? (round off to 1 decimal place)
G-XEC-2019-22	NUM	11.0 to 12.5	Magnetism	An iron bar magnet having coercivity of 7000 A $m^(-1)$ is to be demagnetized. The bar is introduced fully inside a 0.25 m long solenoid having 150 turns of wire. The electric current(in amperes) required to generate the necessary magnetic field is? (round off to 1 decimal place)
G-XEC-2020-1	MCQS-NUM	C	Phase transition	A Pb-Sn sample of eutectic composition, containing α- and β- phases, is examined in a scanning electron microscope. The α- phase contains ~97 wt% Pb(atomic number 82) while β-phase contains ~99 wt% Sn(atomic number 50). The ratio of number of backscattered electrons escaping from α-phase to that from β-phase would be: (A) Less than 1 (B) Equal to 1 (C) Greater than 1 (D) Equal to 0
G-XEC-2020-2	MCQS	B	Miscellaneous	Smallest of minimum feature size that can be theoretically resolved in an optical microscope does NOT depend on: (A) Refractive index of the medium between the lens and the focal point (B) Intensityh of radiation (C) Wavelength of radiation (D) Numerical aperture of the objective lens
G-XEC-2020-4	MCQS	A	Atomic structure	Density of states, D(E) in a three dimensional solid varies with energy(E) as (A) $E^(1/2)$ (B) $E^(0)$ (C) $E^(-1/2)$ (D) $E^(3/2)$
G-XEC-2020-8	NUM	157 to 159	Thermodynamics	A ceramic material is periodically heated and cooled between 25° C and a higher temperature $T_f$. During thermal cycling, the material remains dimensionally constrained. The material can withstand a maximum compressive stress of 200 MPa without failure. Material's coefficient of thermal expansion is 7.5* $10^(-6)°C^(-1)$ and modulus of elasticity (E) is 200GPa. The lowest value of $T_f$( in °C) at which material will fail is?(round off to the nearest integer.). Assume that there is no plastic deformation during thermal cycling.
G-XEC-2020-9	NUM	1.9 to 2.1	Thermodynamics	Given that $γ_(sl)$ (solid liquid interfacial energy) is 0.18 $J.m^(-2)$ and $ΔG_v$ (change in volume free energy upon transformation from liquid to solid) is $T_s$ is 0.18*$10^(9)J.m^(-3)$. During homogeneous solidification of a liquid metal, the radius of critical nucleus(in nanometer, nm) at a temperature $T_s$ which is below the melting point($T_m$), is ? (round-off to one decimal place).
G-XEC-2020-10	MCQS	B	Material manufacturing	Read the two statements related to sintering and select the correct option. Statement-1: Sintering in vacuum leads to improved densification as compared to sintering under ambient (at atmospheric pressure) condition. Statement-2: Closed pores formed during sintering inhibit full densification. (A) Both Statement-1 and Statement-2 are FALSE. (B) Both statement-1 and Statement-2 are TRUE. (C) Statement-1 is TRUE but Statement -2 is FALSE. (D) Statement-1 is FALSE but Statement-2 is TRUE.
G-XEC-2020-11	MATCH	C	Material manufacturing	Select the correct option that appropriately matches the process to the material/product that can be fabricated using them. Process: [(I) Powder Processing, (II) Spin coating, (III) Czochralski process, (IV) Chemical vapor deposition] Material/Product: [(P) Organic semiductor thin films, (Q) Single crystal silicon, (R)Poly-silicon, (S) Porous bronze bearings] Options: (A) I-S, II-P, III-R, IV-Q (B) I-S, II-R, III-Q, IV-P (C) I-S, II-P, III-Q, IV-R (D) I-P, II-R, III-Q, IV-S
G-XEC-2020-14	NUM	69 to 69	Material manufacturing	In an industry, the probability of an accident occurring in a given month is 1/100. Let P(n) denote the probability that there will be no accident over a period of ‘n’ months. Assume that the events of individual months are independent of each other. The smallest integer value of ‘n’ such that P(n) ≤ ½ is? (round off to the nearest integer)
G-XEC-2021-1	MCQS	C	Phase transition	Condition to be satisfied for α and β phases to be in equilibrium in a two component (A and B) system at constant temperature and pressure is (Given: 𝝁 is the chemical potential) (A) entropy of the system should be maximum (B) Gibbs energy of the system should be minimum and $(𝜇_𝐴)^𝛼$ = $(𝜇_B)^𝛼$ , $(𝜇_𝐴)^𝛽$ = $(𝜇_B)^𝛽$ (C) Gibbs energy of the system should be minimum and $(𝜇_𝐴)^𝛼$ = $(𝜇_A)^𝛽$ , $(𝜇_B)^𝛼$ = $(𝜇_B)^𝛽$ (D) Helmholtz energy should be minimum
G-XEC-2021-2	MCQS	C	Material Applications	Amino acids react to form peptides and proteins. This process is known as (A) addition polymerization (B) nucleophilic substitution (C) condensation polymerization (D) hydration
G-XEC-2021-3	MCQS	D	Atomic structure	The most favoured slip system in face centered cubic metal is (A) (111) [110] (B) (110) [1 -1 1] (C) (1 1 -1) [112] (D) (111) [1 -1 0]
G-XEC-2021-4	MCQS	C	Electrical	The dielectric constant of a material at ultraviolet frequencies is mainly due to (A) dipolar polarizability (B) ionic polarizability (C) electronic polarizability (D) interfacial polarizability
G-XEC-2021-5	MATCH	C	Phase transition	Match the different transformations/reactions in Column I with the most suitable information in Column II. Column I: [(P) Eutectoid reaction, (Q) Martensitic transformation, (R) Precipitation reaction] Column II: [(1) involves no diffusion, (2) one solid phase transforms into two solid phases, (3) occurs in supersaturated solutions] Options: (A) P-2; Q-3; R-1 (B) P-1; Q-2; R-3 (C) P-2; Q-1; R-3 (D) P-3; Q-2; R-1
G-XEC-2021-6	MCQS	B	Material characterization	In scanning electron microscopy, the resolution of backscattered electron (BSE) image is poorer compared to that of secondary electron (SE) image, because (A) energy of BSE is lower (B) sampling volume of BSE is larger (C) yield of BSE is lower (D) sampling volume of SE is larger
G-XEC-2021-7	MCQS	B	Thermodynamics	Which of the following deposition conditions favour the formation of larger grains in thin film? (A) Low deposition rate and low substrate temperature (B) Low deposition rate and high substrate temperature (C) High deposition rate and low substrate temperature (D) High deposition rate and high substrate temperature
G-XEC-2021-8	MCQS	B; D	Thermodynamics	A metal has a melting point of 600 °C. By rapid cooling, liquid metal can be made to solidify either at 500 °C or 400 °C or 300 °C. Critical size of the solid nuclei is (A) same for solidification at 400 °C and 500 °C (B) smaller for solidification at 400 °C as compared to solidification at 500 °C (C) larger for solidification at 400 °C as compared to solidification at 500 °C (D) the smallest for solidification at 300 °C
G-XEC-2021-10	MATCH	B	Material characterization	In the context of scanning electron microscopy, match the information in Column I with most appropriate information in Column II. Column I: [(P) Secondary electrons, (Q) Backscattered electrons, (R) Characteristic X-rays, (S) Diffracted backscattered electrons] Column II: [(1) Crystallographic orientation of grains, (2) Failure analysis of fractured surfaces, (3) Chemical composition analysis, (4) Distinguishing chemically distinct phases] Options: (A) P-3; Q-2; R-1; S-4 (B) P-2; Q-4; R-3; S-1 (C) P-1; Q-3; R-2; S-4 (D) P-4; Q-2; R-1; S-3
G-XEC-2021-11	MATCH	C	Material processing	Match the heat treatment processes given in Column I with the most suitable outcomes in Column II. Column I: [(P) Quenching, (Q) Annealing, (R) Tempering, (S) Carburizing] Column II: [(1) hardens the steel, (2) softens the cold worked steel, (3) toughens the steel, (4) hardens the surface of steel] Options: (A) P-3; Q-2; R-1; S-4 (B) P-2; Q-4; R-3; S-1 (C) P-1; Q-2; R-3; S-4 (D) P-1; Q-3; R-4; S-2
G-XEC-2021-13	MCQS	A; B	Atomic structure	X-ray diffraction peak broadening enables the estimation of (A) crystallite size of the material (B) microstrain in the material (C) precise lattice parameter (D) residual macrostress acting on the material
G-XEC-2021-16	NUM	38 to 42	Phase transition	A binary A-B alloy has α and β phases at equilibrium. The ratio of weight percentages (wt.%) of α to β is 4. The wt.% of A in α and β phases is 70 and 20, respectively. The wt.% of B in the alloy is? (round off to nearest integer)
G-XEC-2021-21	NUM	2.10 to 2.14	Material manufacturing	A certain ceramic has a theoretical density and sintered density of 6.76 $gcm^(−3)$ and 6.60 g $cm^(−3)$ , respectively. The green compact has 18 volume percent porosity. For a sintered cube of side 2 cm, the required side of the cubic green compact in cm is? (round off to 2 decimal places)
G-XEC-2022-1	MCQS	B	Atomic structure	Number of atoms per unit area of the (110) plane of a body centered cubic crystal, with lattice parameter ‘𝑎’, is (A) 1/$a^2$ (B) √2/$a^2$ (C) 1/√3$a^2$ (D) 1/√2$a^2$
G-XEC-2022-2	MATCH	C	Atomic structure	Match the following materials with their corresponding bonding types. Material : [P: $Cu_(0.5)Al_(0.5)$, Q: ZnS, R: $Na_(2)O$, S: $Li_(4)SiO_(4)] Bonding: [1: Ionic, 2: Covalent, 3: Metallic, 4: Mixed ] Options: (A) P - 4; Q - 2; R - 3; S - 1 (B) P - 3; Q - 4; R - 2; S - 1 (C) P - 3; Q - 2; R - 1; S - 4 (D) P - 3; Q - 1; R - 4; S - 2
G-XEC-2022-3	MCQS	C	Mechanical	In an ideal rubber, the primary factor responsible for elasticity up to small strains is (A) Change in both enthalpy and entropy (B) Change in enthalpy, but no change in the entropy (C) No change in enthalpy, but change in the entropy (D) Neither a change in enthalpy, nor a change in the entropy
G-XEC-2022-5	MCQS	C	Material characterization	A differential scanning calorimetry (DSC) experiment tracks the heat flow into or out of a system as a function of temperature. If the experiments given in the options below are performed at 1 atmospheric pressure, then in which case will the DSC thermogram exhibit a spike, either upward or downward? (A) Heating 10 mg of pure Cu from 323 K to 673 K (B) Cooling pure water from 323 K to 278 K (C) Heating pure ice from 263 K to 284 K (D) Cooling a Pb-Sn alloy at the eutectic composition from 323 K to 273 K
G-XEC-2022-6	MCQS	D	Material Applications	Which one of the following solvent environments will likely result in swelling of solid polystyrene? (A) 0.1 M NaOH in $H_(2)O$ (B) HCl (aq.) of pH = 6 (C) Distilled water (D) Benzene
G-XEC-2022-9	NUM	2.20 to 2.30	Electrical	Given: E° ($Li^(+)$/Li) = -3.04 V versus Standard Hydrogen Electrode, E° ($Zn^(2+)$/Zn) = -0.77 V versus Standard Hydrogen Electrode. An electrochemical reaction is known to occur at +4.50 V against a $Li^(+)$/Li reference electrode. The potential(in volts) of the same reaction against a $Zn^(2+)$/Zn reference electrode is? (Round off to two decimal places).
G-XEC-2022-10	MCQS	C	Phase transition	For a binary system at constant pressure, there are two types of invariant reactions: (i) α ↔ β + γ (ii) α + β ↔ γ Analogously, how many different types of invariant reactions may exist under variable temperature and pressure, for a binary system? (A) 1 (B) 2 (C) 3 (D) 4
G-XEC-2022-11	MCQS	C	Thermodynamics	For a glass marginally below its glass transition temperature, which one of the following statements is true? (A) Glass has higher enthalpy than both the corresponding crystalline and liquid phases (B) Glass has lower enthalpy than both the corresponding crystalline and liquid phases (C) Glass has higher entropy than the corresponding crystalline phase and lower entropy than the corresponding liquid phase (D) Glass has lower entropy than the corresponding crystalline phase and higher entropy than the corresponding liquid phase
G-XEC-2022-14	MCQS	C	Mechanical	During the ageing of a homogenized Al-Cu alloy (1 to 4 wt.% Cu) below the GP zone solvus, hardness of the alloy: (A) increases monotonically (B) decreases monotonically (C) first increases and then decreases (D) first decreases and then increases
G-XEC-2022-16	MCQS	A,C	Phase transition	For a diffusional transformation (i.e., growth of β precipitates in an α matrix), which of the following is/are true with increasing degree of undercooling? (A) Rate of transformation first increases and then decreases (B) Rate of transformation first decreases and then increases (C) Thermodynamic driving force increases monotonically (D) Mobility of atoms in α matrix remains unchanged
G-XEC-2022-17	NUM	0.5 to 0.5	Phase transition	A two-phase (α + β) mixture of an A-B binary system has the following properties: (i) Phase α has equal weight percentages of A and B. (ii) Phase β has twice the mole fraction of A compared to B. (iii) The two-phase mixture has equal amounts of α and β. (iv) Atomic mass of A is twice that of B. The mole fraction of A in the resultant two-phase mixture is? (Round off to one decimal)
G-XEC-2022-22	NUM	5.64 to 5.73	Atomic structure	The third peak in the X-ray diffraction pattern of a face-centered cubic crystal is at 2𝜃 value of 45°, where 2𝜃 is the angle between the incident and reflected rays. The wavelength of the monochromatic X-ray beam is 1.54 Å. Considering first-order reflection, the lattice parameter(in Å) of the crystal is? (Round off to two decimal places)
G-META-12-6	MCQS	A	Material Applications	When a zinc metal rod is immersed in dilute hydrochloric acid, it results in (A) Evolution of hydrogen (B) Evolution of chlorine (C) Evolution of oxygen (D) No evolution of any gas
G-META-12-7	MCQS-NUM	B	Fluid	A fluid is flowing with a velocity of 0.5 m/s on a plate moving with a velocity of 0.01 m/s in the same direction. The velocity at the interface of the fluid and plate is (A) 0.0 m/s (B) 0.01 m/s (C) 0.255 m/s (D) 0.50 m/s
G-META-12-8	MCQS	D	Material manufacturing	Hot metal at 1700 K is poured in a sand mould that is open at the top. Heat loss from the liquid metal takes place by (A) Radiation only (B) Radiation and conduction only (C) Radiation and convection only (D) Radiation, conduction and convection
G-META-12-9	MCQS	A	Atomic structure	Which one of the following is an equilibrium defect? (A) Vacancies (B) Dislocations (C) Stacking faults (D) Grain boundaries
G-META-12-10	MCQS	A	Material manufacturing	Floatation beneficiation is based on the principle of (A) Mineral surface hydrophobicity (B) Gravity difference (C) Chemical reactivity (D) Particle size difference
G-META-12-11	MCQS	B	Material Applications	Copper can be reduced from acidic copper sulphate solution by (A) Silver (B) Iron (C) Carbon (D) Lead
G-META-12-12	MCQS	C	Material manufacturing	Which one is NOT an agglomeration process? (A) Nodulizing (B) Briquetting (C) Roasting (D) Pelletizing
G-META-12-13	MCQS	D	Material manufacturing	During LD blow in steelmaking the impurity that gets removed first is (A) Carbon (B) Phosphorous (C) Manganese (D) Silicon
G-META-12-14	MCQS	A	Thermodynamics	During the solidification of a pure metal, it was found that dendrites are formed. Assuming that the liquid-solid interface is at the melting temperature, the temperature from the interface into the liquid (A) Decreases (B) Increases (C) Remains constant (D) Increases and then decreases
G-META-12-15	MCQS-NUM	B	Atomic structure	A peak in the X-ray diffraction pattern is observed at 2θ = 78°, corresponding to {311} planes of an fcc metal, when the incident beam has a wavelength of 0.154 nm. The lattice parameter of the metal is approximately (A) 0.6 nm (B) 0.4 nm (C) 0.3 nm (D) 0.2 nm
G-META-12-16	MCQS	B	Atomic structure	If d is the inter-planar spacing of the planes {h k l}, the inter-planar spacing of the planes {nh nk nl}, n being an integer, is (A) d (B) d/n (C) nd (D) d/$n^2$
G-META-12-17	MCQS	C	Electrical	As temperature increases, the electrical resistivities of pure metals ($ρ_m$) and intrinsic semiconductors ($ρ_s$) vary as follows (A) Both $ρ_m$ and $ρ_s$ increase (B) Both $ρ_m$ and $ρ_s$ decrease (C) $ρ_m$ increases and $ρ_s$ decreases (D) $ρ_m$ decreases and $ρ_s$ increases
G-META-12-18	MCQS	B	Thermodynamics	At equilibrium spacing in a crystalline solid, which of the following is true for net inter-atomic force (F) and potential energy (U) (A) F is zero and U is zero (B) F is zero and U is minimum (C) F is minimum and U is zero (D) F is minimum and U is minimum
G-META-12-19	MCQS	D	Thermodynamics	The property of a material that CANNOT be significantly changed by heat treatment is (A) Yield strength (B) Ultimate tensile strength (C) Ductility (D) Elastic modulus
G-META-12-20	MCQS	A	Atomic structure	A unit dislocation splits into two partial dislocations. The correct combination of the Burgers vectors of the partial dislocations for a given unit dislocation having Burgers vector (a/2)[1 -1 0] is (A) (a/6)[2 -1 1] and (a/6)[1 -2 -1] (B) (a/6)[1 -1 2] and (a/6)[-1 -2 1] (C) (a/6)[1 1 -2] and (a/6)[2 -1 -1] (D) (a/6)[2 1 1] and (a/6)[1 2 -1]
G-META-12-21	MCQS	C	Mechanical	A polymer matrix composite is reinforced with long continuous ceramic fibres aligned in one direction. The Young’s moduli of the matrix and fibres are $E_m$ and $E_f$ respectively, and the volume fraction of the fibres is f. Assuming iso-stress condition, Young’s modulus of the composite $E_C$ in a direction perpendicular to the length of fibres, is given by the expression (A) $E_C$ = (1-f)$E_m$ + f$E_f$ (B) $E_C$ = f$E_m$ + (1-f)$E_f$ (C) 1/$E_C$ = [(1-f)/$E_m$] + f/$E_f$ (D) 1/$E_C$ = [f/$E_m$] + (1-f)/$E_f$
G-META-12-24	MCQS	C	Material manufacturing	The riser is designed such that the melt in the riser solidifies (A) Before casting solidifies (B) At the same time as casting solidifies (C) After casting solidifies (D) Irrespective of the solidification of the casting
G-META-12-25	MCQS	D	Atomic structure	Radiography technique of detecting defects is based on the principle of (A) Diffraction (B) Reflection (C) Interference (D) Absorption
G-META-12-31	MATCH	A	Transport phenomena	Match the principles given in Group I with corresponding corrosion terminology in Group II: Group I : [P. Electrode polarization, Q. Passivity, R. Selective leaching, S. Grain boundary precipitation] Group II: [1. Dezincification, 2. Intergranular attack, 3. Over voltage, 4. Surface oxide film] Options: (A) P-3, Q-4, R-1, S-2 (B) P-3, Q-4, R-2, S-1 (C) P-4, Q-2, R-1, S-3 (D) P-2, Q-1, R-4, S-3
G-META-12-32	MCQS	C	Electrical	Identify the correct combination of the following statements: P. Hydrogen electrode is a standard used to measure redox potentials Q. Activation polarization refers to electrochemical processes controlled by reaction sequence at metal-solution interface R. Potential-pH diagrams can be used to predict corrosion rates of metals S. Cathodic protection can use sacrificial anodes such as magnesium (A) P, Q and R (B) Q, R and S (C) P, Q and S (D) P, R and S
G-META-12-33	MCQS-NUM	B	Thermodynamics	Consider a reaction with activation energy of 8.314 kJ/mol that takes place at 300 K. If the reaction rate is to be tripled, the temperature of the reaction should be (A) 174.5 K (B) 447.5 K (C) 600.5 K (D) 847.5 K
G-META-12-34	MATCH	D	Material processing	Match the processes in Group I with the objectives in Group II: Group I : [P. Vacuum Arc Degassing (VAD), Q. LD, R. COREX, S. Blast Furnace] Group II : [1. Primary iron making, 2. Secondary steel making, 3. Direct smelting, 4. Primary steel making] Options: (A) P-3, Q-4, R-2, S-1 (B) P-4, Q-3, R-1, S-2 (C) P-3, Q-2, R-1, S-4 (D) P-2, Q-4, R-3, S-1
G-META-12-35	MCQS-NUM	D	Thermodynamics	The reduction of FeO with CO gas in co-current flow is given by the following equation: FeO + CO = Fe + $CO_2$ ∆G°= 8120 J at 1173K. The ratio of $p_(CO)/p_(CO_2)$ for this reaction at 1173 K is (A) 0.0 (B) 0.25 (C) 0.44 (D) 2.3
G-META-12-36	MCQS-NUM	B	Material manufacturing	The sulphide capacity ($C_S$) of liquid slag of composition 55 wt.% CaO, 20 wt.% SiO2, 15 wt.% Al2O3, and 10 wt.% MgO is given by the following equation: log $C_s$ = 3.44* [$X_(CaO)$ + 0.1$X_(MgO)$ -0.8$X_(Al_(2)O_(3)) - $X_(SiO_2)$] - (9894/T) + 2.05 where, X is mole fraction of the respective components. Atomic weights of Ca, Mg, Si, Al and O are 40, 24, 28, 27 and 16 respectively. The value of $C_S$ at 1900 K is (A) 0.0009 (B) 0.009 (C) 0.09 (D) 0.9
G-META-12-39	MATCH	C	Phase transition	Match the phases of steel in Group I with the crystal structures in Group II: Group I: [P. Martensite, Q. Cementite, R. Austenite, S. Ferrite] Group II: [1. bcc, 2. fcc, 3. bct, 4. Orthorhombic] Options: (A) P-3, Q-4, R-1, S-2 (B) P-2, Q-3, R-1, S-4 (C) P-3, Q-4, R-2, S-1 (D) P-4, Q-3, R-2, S-1
G-META-12-40	MCQS	A	Material manufacturing	Arrange the following in terms of increasing severity of quench: P. Oil quenching, Q. Water quenching, R. Water quenching with agitation, S. Brine quenching (A) P<Q<R<S (B) Q<R<P<S (C) P<Q<S<R (D) Q<P<R<S
G-META-12-41	MCQS	D	Material processing	Regarding recrystallization, which one of the following statements is NOT correct? (A) Higher the amount of cold work, lower is the recrystallization temperature (B) Higher the recovery, higher is the recrystallization temperature (C) Higher the temperature of cold work, higher is the recrystallization temperature (D) Finer the initial grain size, higher is the recrystallization temperature
G-META-12-43	MATCH	C	Mechanical	Match the phenomena listed in Group I with the possible mechanisms in Group II: Group I: [P. Fatigue, Q. Creep, R. Strain hardening, S. Yield point phenomenon] Group II: [1. Grain boundary sliding, 2. Slip band extrusion and intrusion, 3. Cottrell atmosphere, 4. Dislocation interaction] Options: (A) P-2, Q-3, R-4, S-1 (B) P-2, Q-4, R-3, S-1 (C) P-2, Q-1, R-4, S-3 (D) P-1, Q-2, R-4, S-3
G-META-12-44	MCQS-NUM	C	Mechanical	Fracture stress for a brittle material having a crack length of 1 µm is 200 MPa. Fracture stress for the same material having a crack length of 4 µm is (A) 200 MPa (B) 150 MPa (C) 100 MPa (D) 50 MPa
G-META-12-45	MCQS-NUM	B	Mechanical	The flow stress (σ) of an alloy varies with strain rate (ε) as σ = 100* $(ε)^(0.1)$ MPa. When the alloy is hot extruded from 10 cm diameter to 5 cm diameter at a speed of 2 cm/s, the flow stress is (A) 1000 MPa (B) 105 MPa (C) 150 MPa (D) 1050 MPa
G-META-12-46	MCQS	C	Material processing	Determine the correctness or otherwise of the following Assertion (a) and Reason (r). Assertion : During rolling, front tension and (or) back tension are (is) employed to decrease rolling load. Reason : Roll pressure decreases due to lowering of flow stress as a result of front tension/back tension. (A) a is false but r is true (B) a is true and r is also true, but r is not the reason for a (C) a is true and r is also true, and r is the reason for a (D) a is true but r is false
G-META-12-47	MATCH	C	Material processing	Match the defects listed in Group I with the processes listed in Group II: Group I : [P. Cold shut, Q. Earing, R. Alligatoring, S. Shrinkage porosity] Group II : [1. Rolling, 2. Forging, 3. Deep drawing, 4. Fusion welding] Options: (A) P-2, Q-4, R-1, S-4 (B) P-2, Q-4, R-3, S-1 (C) P-2, Q-3, R-1, S-4 (D) P-4, Q-1, R-2, S-3
G-META-12-49	MCQS-NUM	B	Fluid	A steel ball (density $ρ_(steel)$ = 7200 kg/$m^(3)$) is placed in an upward moving liquid Al (density $ρ_(Al)$ = 2360 kg/$m^(3)$, viscosity $μ_(Al)$ = 1$10^(–3)$ Pa.s and Reynolds number = 5$10^(5)$). The force (F) exerted on the steel ball is expressed as: F = f π $R^(2)$ ($ρ_(Al)$ $v^2$ /2) where, f is friction factor (=0.2), v is the velocity of liquid Al and R is the radius of steel ball. The terminal velocity of a fine spherical steel particle having diameter $d_p$, in µm range, if allowed to fall in a quiescent liquid Al bath, is (A) 5.2$10^6$ $d_(p)^2$ m/s (B) 2.6 $10^6$ $d_(p)^2$ m/s (C) 1.3$10^6$ $d_(p)^2$ m/s (D) 6.6 $10^5$ $d_(p)^2$ m/s
G-META-12-52	MCQS-NUM	A	Atomic structure	A material with grain size of ASTM No. 6 has a lattice frictional stress 100 MN/$m^2$ and locking parameter (Hall-Petch constant) 0.10 MN/$m^(1.5)$. Grain size of the material is approximately (A) 45 µm (B) 35 µm (C) 4.5 µm (D) 3.5 µm
G-META-12-53	MCQS-NUM	B	Mechanical	A material with grain size of ASTM No. 6 has a lattice frictional stress 100 MN/$m^2$ and locking parameter (Hall-Petch constant) 0.10 MN/$m^(1.5)$. Yield strength of the material is approximately (A) 100 MPa (B) 115 MPa (C) 165 MPa (D) 215 MPa
G-META-13-3	MCQS	A	Thermodynamics	In a binary system A-B, $ε_(AA)$, $ε_(BB)$ and $ε_(AB)$ correspond to A-A, B-B and A-B bond energies respectively. The miscibility gap will occur if (A) $ε_(AB)$ > ½ ($ε_(AA)$ + $ε_(BB)$) (B) $ε_(AB)$ < ½ ($ε_(AA)$ + $ε_(BB)$) (C) $ε_(AB)$ = ½ ($ε_(AA)$ + $ε_(BB)$) (D) $ε_(AB)$ < ¼ ($ε_(AA)$ + $ε_(BB)$)
G-META-13-5	MCQS	A	Atomic structure	With respect to the matrix of Al-Cu alloys, G-P zones are (A) coherent (B) incoherent (C) semi-coherent (D) chemically indistinguishable

G-XEC-2017-20

NUM

1.35 to 1.37

Electrical

Give: Charge of an electron: 1.6* $10^(-19)$C. Copper is an FCC metal with lattice paramenter of 3.62 Å. Hall effect measurement shows electron mobility to be 3.2 * $10^(-3)m^(2)V^(-1)s^(-1)$. Electrical resistivity of copper is 1.7* $10^(-8)$ Ωm. The average number of free electrons per atom in copper is ?

G-XEC-2017-21

MCQS-NUM

C

Atomic structure

In an ionic solid the cation and the anion have ionic radii as 0.8 Å and 1.6 Å respectively. The maximum coordination number of the cation in the structure will be (A) 3 (B) 4 (C) 6 (D) 8

G-XEC-2017-22

MCQS

A

Magnetism

Which of the following statement(s) is/are true regarding susceptibility of a material (i) Magnetic susceptibility is positive for a diamagnetic material (ii) Magnetic susceptibility is negative for a diamagnetic material (iii) Magnetic susceptibility is negative for an antiferromagnetic material (iv) Magnetic susceptibility is positive for a paramagnetic material (A) (ii) and (iv) (B) (i) and (iii) (C) (ii) and (iii) (D) (i) and (iv)

G-XEC-2018-1

MCQS

C

Mechanical

The stress ratio for a completely reversed cyclic loading during a fatigue test is (A) 0 (B) 1 (C) -1 (D) -1/2

G-XEC-2018-2

MCQS

A

Atomic structure

Minimum symmetry that a cubic crystal must possess is (A) four 3-fold rotation axes. (B) three 4-fold rotation axes. (C) three orthogonal mirror planes. (D) centre of symmetry.

G-XEC-2018-3

MCQS

B

Magnetism

If a material is repelled in an external magnetic field then it is (A) Ferromagnetic (B) Diamagnetic (C) Paramagnetic (D) Antiferromagnetic

G-XEC-2018-4

MCQS

C

Thermodynamics

An electron makes a transition from the valence band to the conduction band in an indirect band gap semiconductor. Which one of the following is true? (A) Energy of the electron decreases. (B) A photon is emitted in the process. (C) A phonon is annihilated in the process. (D) A photon is created in the process.

G-XEC-2018-5

MCQS

A

Atomic structure

Which one of the following is the characteristic of a screw dislocation? (A) Dislocation line and Burgers vector are parallel. (B) Direction of motion of dislocation is parallel to the Burgers vector. (C) Atomic displacement due to the movement of the dislocation is in the direction of the motion of the dislocation line. (D) It has a unique slip plane.

G-XEC-2018-6

MCQS-NUM

D

Atomic structure

The number of vibrational degrees of freedom for a non-linear triatomic molecule are (A) 9 (B) 6 (C) 4 (D) 3

G-XEC-2018-10

MATCH

B

Phase transition

Match the invariant reactions in Column I with the names in Column II (L is liquid phase, and α , β, γ are solid phases). All reactions proceed to the right on cooling. Column I : [(P) 𝐿 ⇄ 𝛼 + 𝛽, (Q) 𝐿 + 𝛼 ⇄ 𝛽, (R) 𝛾 ⇄ 𝛼 + 𝛽, (S) 𝛼 + 𝛽 ⇄ 𝛾] Column II: [(1) Monotectic, (2) Peritectoid, (3) Peritectic, (4) Eutectoid, (5) Eutectic] Options: (A) P-5, Q-1, R-4, S-3 (B) P-5, Q-3, R-4, S-2 (C) P-5, Q-1, R-2, S-4 (D) P-2, Q-1, R-4, S-5

G-XEC-2018-11

MCQS-NUM

A

Electrical

Consider the following anodic (oxidation) reaction in an acidic solution: 𝑀𝑔 ⟶ $𝑀𝑔^(+2)$ + $2𝑒^(-)$. If 48250 Coulomb charge is produced during this anodic reaction then the amount of Mg (in g) dissolved into the solution is (Given: Faraday Constant = 96500 C/mole of electrons, Atomic weight of Mg = 24) (A) 6 (B) 12 (C) 24 (D) 48

G-XEC-2018-12

MCQS-NUM

B

Electrical

An intrinsic semiconductor has conduction electron concentration, n = $10^(12)$ $cm^(-3)$. The mobility of both electrons and holes are identical = 4 * $10^4$ $cm^2$ $V^(-1)$ $s^(-1)$. If a voltage of 100 V is applied on two parallel end faces of the cube (edge length 1 cm) through Ohmic contacts, the current through the cube would be (in mA) (Given: charge of electron = 1.6 * $10^(-19)$ C) (A) 640 (B) 1280 (C) 6400 (D) 12800

G-XEC-2018-13

NUM

430 to 500

Mechanical

An infinite plate with a through-thickness crack of length 2 mm is subjected to a tensile stress (as shown in the figure). Assuming the plate to be linear elastic, the fracture stress in MPa (round off to the nearest whole number). (Given: Fracture toughness, $K_(1C)$ = 25 MPa √𝑚)

G-XEC-2018-15

NUM

2.60 to 2.70

Material Applications

(Given: Density of water = 1.00 g $cm^(-3)$). A sintered sample was weighed in air and water using an analytical balance. The mass of the sample in air is 2.67 g and its apparent mass in water is 1.67 g. Calculate the density of the sample in g $cm^(-3)$ (give answer up to 2 decimal places)

G-XEC-2018-18

NUM

132 to 132

Thermodynamics

When 3 identical non-interacting spin ½ particles are put in an infinite potential well, the ground state energy of the system is 18 meV. If instead, seven particles are put inside the potential well, the new ground state energy in meV is?

G-XEC-2018-22

NUM

1420 to 1480

Thermodynamics

Given: Activation energy Q = 148 kJ $mol^(-1)$, Gas constant, R = 8.314 J $mol^(-1)$ $K^(-1)$. Mild steel is carburized at 1300 K for 1 hour to obtain a certain case depth. Keeping the time as 1 hour, the case depth can be doubled by increasing the temperature to what temperature(in K)? (round off to the nearest whole number)

G-XEC-2019-1

MCQS

B

Miscellaneous

On decreasing the objective aperture size in an optical microscope (A) the spherical aberration increases (B) the depth of field increases (C) the diffraction-limited resolution increases (D) the astigmatism increases

G-XEC-2019-3

MCQS

A

Atomic structure

In NaCl, the substitution of a $Na^(+1)$ ion by a $Ca^(2+)$ ion would most probably lead to (A) the formation of a $Na^(+1)$ vacancy (B) the creation of a Cl‾ interstitial (C) the formation of a Cl‾ vacancy (D) the formation of a $Na^(+1)$ and Cl‾ vacancy pair

G-XEC-2019-4

MCQS

A

Mechanical

Which one of the following is time-independent? (A) Elastic deformation (B) Anelastic deformation (C) Viscoelastic deformation (D) Creep deformation

G-XEC-2019-5

MCQS-NUM

B

Transport phenomena

(Given: Diffusion coefficients of copper in aluminium at 400 °C and 500 °C are 5*$10^(-14)m^(2)s^(-1)$ and 6*$10^(-13)m^(2)s^(-1)$, respectively). Copper is diffused into aluminium at 400 °C for 100 hours to obtain a certain concentration at a given depth. In another experiment conducted at 500 °C, to achieve the same concentration of copper at the same depth, the time required in hours is (A) 7.33 (B) 8.33 (C) 9.33 (D) 10.33

G-XEC-2019-6

MCQS-NUM

B

Material manufacturing

(Given: atomic weight C = 12, Fe = 56). If carbon (C) in iron (Fe) is 6 percent by weight, then its atomic percent is approximately (A) 13 (B) 23 (C) 30 (D) 50

G-XEC-2019-7

MCQS

C

Thermodynamics

GaAs has advantage over silicon when used in intergrated circuits at low power because it has (A) larger band gap (B) more than one element (C) higher electron mobility (D) higher hole mobility

G-XEC-2019-8

MCQS

D

Material characterization

Glass transition temperature of a polymer can be determined by (A) Thermo-gravimetric analysis (B) Raman spectroscopy (C) NMR spectroscopy (D) Differential scanning calorimetry

G-XEC-2019-9

MCQS-NUM

B

Thermodynamics

(Given: energy gap of Ge = 0.67 eV, Planck’s constant h = 6.63 * $10^(-34)$ J s, velocity of light c = 3 * $10^(8)ms^(-1)$ and 1 eV = 1.6*$10^(-19)$ J ). The maximum wavelength of radiation to which Germanium (Ge) is opaque will be (A) 0.8 μm (B) 1.8 μm (C) 2.8 μm (D) 4.8 μm

G-XEC-2019-10

MCQS

B

Atomic structure

(Given: atomic weight of H = 1, C = 12, F = 19 and Cl = 35.5). An alternating copolymer has number-averaged molecular weight of $10^(5)gmol^(-1)$ and degree of polymerization of 2210. If one of the repeat units is ethylene, the other one is (A) $−CH_2−CH(CH_3)−$ (B) $−CH_2−CHCl−$ (C) $−CF_2−CF_2−$ (D) $−CH_2−CH(C_6H_5)−$

G-XEC-2019-11

MATCH

B

Material manufacturing

Match the sintering processes in column I with the most suitable products in column II. Coloumn I: [(P) Solid state sintering, (Q) Liquid phase sintering, (R) Spark plasma sintering, (S) Laser sintering] Coloumn II: [(1) Carbon nanotube products, (2) Mixture of Cu and Zn powder products, (3) Iron powder products, (4) 3D printed products] Options: (A) P-4; Q-1; R-2; S-3 (B) P-3; Q-2; R-1; S-4 (C) P-3; Q-2; R-4; S-1 (D) P-2; Q-3; R-1; S-4

G-XEC-2019-12

MCQS

B

Material manufacturing

Which one of the following conditions will NOT favour the separation of impurities in zone refining process? (A) Increase in the gap between solidus and liquidus lines (B) Increase in the solubility of impurities in solid as compared to that in liquid phase (C) Agitation of melt (D) Low cooling rate of melt

G-XEC-2019-15

NUM

0.28 to 0.32

Thermodynamics

(Given: Constants A = 6* $10^(-20)$ J $nm^3$, B = 2.1 * $10^(-22)$ J $nm^(7)$). The potential energy, U(r), of a pair of atoms spaced at a distance r in a solid is given by U(𝑟)= −(𝐴/$𝑟^3$) + (𝐵/$𝑟^7$) . The equilibrium distance(in nm) between the atom pair is? (round off to 2 decimal places)

G-XEC-2019-18

NUM

9.2 to 9.6

Thermodynamics

(Given: Planck’s constant h = 6.63 * $10^(-34)$ J s, 1ev = 1.6*$10^(-19)$ J, electron mass = 9.11×$10^(-31)$ kg ). The zero point energy(in ev) of an electron in a box of 0.2 nm width is? (round off to 1 decimal place)

G-XEC-2019-22

NUM

11.0 to 12.5

Magnetism

An iron bar magnet having coercivity of 7000 A $m^(-1)$ is to be demagnetized. The bar is introduced fully inside a 0.25 m long solenoid having 150 turns of wire. The electric current(in amperes) required to generate the necessary magnetic field is? (round off to 1 decimal place)

G-XEC-2020-1

MCQS-NUM

C

Phase transition

A Pb-Sn sample of eutectic composition, containing α- and β- phases, is examined in a scanning electron microscope. The α- phase contains ~97 wt% Pb(atomic number 82) while β-phase contains ~99 wt% Sn(atomic number 50). The ratio of number of backscattered electrons escaping from α-phase to that from β-phase would be: (A) Less than 1 (B) Equal to 1 (C) Greater than 1 (D) Equal to 0

G-XEC-2020-2

MCQS

B

Miscellaneous

Smallest of minimum feature size that can be theoretically resolved in an optical microscope does NOT depend on: (A) Refractive index of the medium between the lens and the focal point (B) Intensityh of radiation (C) Wavelength of radiation (D) Numerical aperture of the objective lens

G-XEC-2020-4

MCQS

A

Atomic structure

Density of states, D(E) in a three dimensional solid varies with energy(E) as (A) $E^(1/2)$ (B) $E^(0)$ (C) $E^(-1/2)$ (D) $E^(3/2)$

G-XEC-2020-8

NUM

157 to 159

Thermodynamics

A ceramic material is periodically heated and cooled between 25° C and a higher temperature $T_f$. During thermal cycling, the material remains dimensionally constrained. The material can withstand a maximum compressive stress of 200 MPa without failure. Material's coefficient of thermal expansion is 7.5* $10^(-6)°C^(-1)$ and modulus of elasticity (E) is 200GPa. The lowest value of $T_f$( in °C) at which material will fail is?(round off to the nearest integer.). Assume that there is no plastic deformation during thermal cycling.

G-XEC-2020-9

NUM

1.9 to 2.1

Thermodynamics

Given that $γ_(sl)$ (solid liquid interfacial energy) is 0.18 $J.m^(-2)$ and $ΔG_v$ (change in volume free energy upon transformation from liquid to solid) is $T_s$ is 0.18*$10^(9)J.m^(-3)$. During homogeneous solidification of a liquid metal, the radius of critical nucleus(in nanometer, nm) at a temperature $T_s$ which is below the melting point($T_m$), is ? (round-off to one decimal place).

G-XEC-2020-10

MCQS

B

Material manufacturing

Read the two statements related to sintering and select the correct option. Statement-1: Sintering in vacuum leads to improved densification as compared to sintering under ambient (at atmospheric pressure) condition. Statement-2: Closed pores formed during sintering inhibit full densification. (A) Both Statement-1 and Statement-2 are FALSE. (B) Both statement-1 and Statement-2 are TRUE. (C) Statement-1 is TRUE but Statement -2 is FALSE. (D) Statement-1 is FALSE but Statement-2 is TRUE.

G-XEC-2020-11

MATCH

C

Material manufacturing

Select the correct option that appropriately matches the process to the material/product that can be fabricated using them. Process: [(I) Powder Processing, (II) Spin coating, (III) Czochralski process, (IV) Chemical vapor deposition] Material/Product: [(P) Organic semiductor thin films, (Q) Single crystal silicon, (R)Poly-silicon, (S) Porous bronze bearings] Options: (A) I-S, II-P, III-R, IV-Q (B) I-S, II-R, III-Q, IV-P (C) I-S, II-P, III-Q, IV-R (D) I-P, II-R, III-Q, IV-S

G-XEC-2020-14

NUM

69 to 69

Material manufacturing

In an industry, the probability of an accident occurring in a given month is 1/100. Let P(n) denote the probability that there will be no accident over a period of ‘n’ months. Assume that the events of individual months are independent of each other. The smallest integer value of ‘n’ such that P(n) ≤ ½ is? (round off to the nearest integer)

G-XEC-2021-1

MCQS

C

Phase transition

Condition to be satisfied for α and β phases to be in equilibrium in a two component (A and B) system at constant temperature and pressure is (Given: 𝝁 is the chemical potential) (A) entropy of the system should be maximum (B) Gibbs energy of the system should be minimum and $(𝜇_𝐴)^𝛼$ = $(𝜇_B)^𝛼$ , $(𝜇_𝐴)^𝛽$ = $(𝜇_B)^𝛽$ (C) Gibbs energy of the system should be minimum and $(𝜇_𝐴)^𝛼$ = $(𝜇_A)^𝛽$ , $(𝜇_B)^𝛼$ = $(𝜇_B)^𝛽$ (D) Helmholtz energy should be minimum

G-XEC-2021-2

MCQS

C

Material Applications

Amino acids react to form peptides and proteins. This process is known as (A) addition polymerization (B) nucleophilic substitution (C) condensation polymerization (D) hydration

G-XEC-2021-3

MCQS

D

Atomic structure

The most favoured slip system in face centered cubic metal is (A) (111) [110] (B) (110) [1 -1 1] (C) (1 1 -1) [112] (D) (111) [1 -1 0]

G-XEC-2021-4

MCQS

C

Electrical

The dielectric constant of a material at ultraviolet frequencies is mainly due to (A) dipolar polarizability (B) ionic polarizability (C) electronic polarizability (D) interfacial polarizability

G-XEC-2021-5

MATCH

C

Phase transition

Match the different transformations/reactions in Column I with the most suitable information in Column II. Column I: [(P) Eutectoid reaction, (Q) Martensitic transformation, (R) Precipitation reaction] Column II: [(1) involves no diffusion, (2) one solid phase transforms into two solid phases, (3) occurs in supersaturated solutions] Options: (A) P-2; Q-3; R-1 (B) P-1; Q-2; R-3 (C) P-2; Q-1; R-3 (D) P-3; Q-2; R-1

G-XEC-2021-6

MCQS

B

Material characterization

In scanning electron microscopy, the resolution of backscattered electron (BSE) image is poorer compared to that of secondary electron (SE) image, because (A) energy of BSE is lower (B) sampling volume of BSE is larger (C) yield of BSE is lower (D) sampling volume of SE is larger

G-XEC-2021-7

MCQS

B

Thermodynamics

Which of the following deposition conditions favour the formation of larger grains in thin film? (A) Low deposition rate and low substrate temperature (B) Low deposition rate and high substrate temperature (C) High deposition rate and low substrate temperature (D) High deposition rate and high substrate temperature

G-XEC-2021-8

MCQS

B; D

Thermodynamics

A metal has a melting point of 600 °C. By rapid cooling, liquid metal can be made to solidify either at 500 °C or 400 °C or 300 °C. Critical size of the solid nuclei is (A) same for solidification at 400 °C and 500 °C (B) smaller for solidification at 400 °C as compared to solidification at 500 °C (C) larger for solidification at 400 °C as compared to solidification at 500 °C (D) the smallest for solidification at 300 °C

G-XEC-2021-10

MATCH

B

Material characterization

In the context of scanning electron microscopy, match the information in Column I with most appropriate information in Column II. Column I: [(P) Secondary electrons, (Q) Backscattered electrons, (R) Characteristic X-rays, (S) Diffracted backscattered electrons] Column II: [(1) Crystallographic orientation of grains, (2) Failure analysis of fractured surfaces, (3) Chemical composition analysis, (4) Distinguishing chemically distinct phases] Options: (A) P-3; Q-2; R-1; S-4 (B) P-2; Q-4; R-3; S-1 (C) P-1; Q-3; R-2; S-4 (D) P-4; Q-2; R-1; S-3

G-XEC-2021-11

MATCH

C

Material processing

Match the heat treatment processes given in Column I with the most suitable outcomes in Column II. Column I: [(P) Quenching, (Q) Annealing, (R) Tempering, (S) Carburizing] Column II: [(1) hardens the steel, (2) softens the cold worked steel, (3) toughens the steel, (4) hardens the surface of steel] Options: (A) P-3; Q-2; R-1; S-4 (B) P-2; Q-4; R-3; S-1 (C) P-1; Q-2; R-3; S-4 (D) P-1; Q-3; R-4; S-2

G-XEC-2021-13

MCQS

A; B

Atomic structure

X-ray diffraction peak broadening enables the estimation of (A) crystallite size of the material (B) microstrain in the material (C) precise lattice parameter (D) residual macrostress acting on the material

G-XEC-2021-16

NUM

38 to 42

Phase transition

A binary A-B alloy has α and β phases at equilibrium. The ratio of weight percentages (wt.%) of α to β is 4. The wt.% of A in α and β phases is 70 and 20, respectively. The wt.% of B in the alloy is? (round off to nearest integer)

G-XEC-2021-21

NUM

2.10 to 2.14

Material manufacturing

A certain ceramic has a theoretical density and sintered density of 6.76 $gcm^(−3)$ and 6.60 g $cm^(−3)$ , respectively. The green compact has 18 volume percent porosity. For a sintered cube of side 2 cm, the required side of the cubic green compact in cm is? (round off to 2 decimal places)

G-XEC-2022-1

MCQS

B

Atomic structure

Number of atoms per unit area of the (110) plane of a body centered cubic crystal, with lattice parameter ‘𝑎’, is (A) 1/$a^2$ (B) √2/$a^2$ (C) 1/√3$a^2$ (D) 1/√2$a^2$

G-XEC-2022-2

MATCH

C

Atomic structure

Match the following materials with their corresponding bonding types. Material : [P: $Cu_(0.5)Al_(0.5)$, Q: ZnS, R: $Na_(2)O$, S: $Li_(4)SiO_(4)] Bonding: [1: Ionic, 2: Covalent, 3: Metallic, 4: Mixed ] Options: (A) P - 4; Q - 2; R - 3; S - 1 (B) P - 3; Q - 4; R - 2; S - 1 (C) P - 3; Q - 2; R - 1; S - 4 (D) P - 3; Q - 1; R - 4; S - 2

G-XEC-2022-3

MCQS

C

Mechanical

In an ideal rubber, the primary factor responsible for elasticity up to small strains is (A) Change in both enthalpy and entropy (B) Change in enthalpy, but no change in the entropy (C) No change in enthalpy, but change in the entropy (D) Neither a change in enthalpy, nor a change in the entropy

G-XEC-2022-5

MCQS

C

Material characterization

A differential scanning calorimetry (DSC) experiment tracks the heat flow into or out of a system as a function of temperature. If the experiments given in the options below are performed at 1 atmospheric pressure, then in which case will the DSC thermogram exhibit a spike, either upward or downward? (A) Heating 10 mg of pure Cu from 323 K to 673 K (B) Cooling pure water from 323 K to 278 K (C) Heating pure ice from 263 K to 284 K (D) Cooling a Pb-Sn alloy at the eutectic composition from 323 K to 273 K

G-XEC-2022-6

MCQS

D

Material Applications

Which one of the following solvent environments will likely result in swelling of solid polystyrene? (A) 0.1 M NaOH in $H_(2)O$ (B) HCl (aq.) of pH = 6 (C) Distilled water (D) Benzene

G-XEC-2022-9

NUM

2.20 to 2.30

Electrical

Given: E° ($Li^(+)$/Li) = -3.04 V versus Standard Hydrogen Electrode, E° ($Zn^(2+)$/Zn) = -0.77 V versus Standard Hydrogen Electrode. An electrochemical reaction is known to occur at +4.50 V against a $Li^(+)$/Li reference electrode. The potential(in volts) of the same reaction against a $Zn^(2+)$/Zn reference electrode is? (Round off to two decimal places).

G-XEC-2022-10

MCQS

C

Phase transition

For a binary system at constant pressure, there are two types of invariant reactions: (i) α ↔ β + γ (ii) α + β ↔ γ Analogously, how many different types of invariant reactions may exist under variable temperature and pressure, for a binary system? (A) 1 (B) 2 (C) 3 (D) 4

G-XEC-2022-11

MCQS

C

Thermodynamics

For a glass marginally below its glass transition temperature, which one of the following statements is true? (A) Glass has higher enthalpy than both the corresponding crystalline and liquid phases (B) Glass has lower enthalpy than both the corresponding crystalline and liquid phases (C) Glass has higher entropy than the corresponding crystalline phase and lower entropy than the corresponding liquid phase (D) Glass has lower entropy than the corresponding crystalline phase and higher entropy than the corresponding liquid phase

G-XEC-2022-14

MCQS

C

Mechanical

During the ageing of a homogenized Al-Cu alloy (1 to 4 wt.% Cu) below the GP zone solvus, hardness of the alloy: (A) increases monotonically (B) decreases monotonically (C) first increases and then decreases (D) first decreases and then increases

G-XEC-2022-16

MCQS

A,C

Phase transition

For a diffusional transformation (i.e., growth of β precipitates in an α matrix), which of the following is/are true with increasing degree of undercooling? (A) Rate of transformation first increases and then decreases (B) Rate of transformation first decreases and then increases (C) Thermodynamic driving force increases monotonically (D) Mobility of atoms in α matrix remains unchanged

G-XEC-2022-17

NUM

0.5 to 0.5

Phase transition

A two-phase (α + β) mixture of an A-B binary system has the following properties: (i) Phase α has equal weight percentages of A and B. (ii) Phase β has twice the mole fraction of A compared to B. (iii) The two-phase mixture has equal amounts of α and β. (iv) Atomic mass of A is twice that of B. The mole fraction of A in the resultant two-phase mixture is? (Round off to one decimal)

G-XEC-2022-22

NUM

5.64 to 5.73

Atomic structure

The third peak in the X-ray diffraction pattern of a face-centered cubic crystal is at 2𝜃 value of 45°, where 2𝜃 is the angle between the incident and reflected rays. The wavelength of the monochromatic X-ray beam is 1.54 Å. Considering first-order reflection, the lattice parameter(in Å) of the crystal is? (Round off to two decimal places)

G-META-12-6

MCQS

A

Material Applications

When a zinc metal rod is immersed in dilute hydrochloric acid, it results in (A) Evolution of hydrogen (B) Evolution of chlorine (C) Evolution of oxygen (D) No evolution of any gas

G-META-12-7

MCQS-NUM

B

Fluid

A fluid is flowing with a velocity of 0.5 m/s on a plate moving with a velocity of 0.01 m/s in the same direction. The velocity at the interface of the fluid and plate is (A) 0.0 m/s (B) 0.01 m/s (C) 0.255 m/s (D) 0.50 m/s

G-META-12-8

MCQS

D

Material manufacturing

Hot metal at 1700 K is poured in a sand mould that is open at the top. Heat loss from the liquid metal takes place by (A) Radiation only (B) Radiation and conduction only (C) Radiation and convection only (D) Radiation, conduction and convection

G-META-12-9

MCQS

A

Atomic structure

Which one of the following is an equilibrium defect? (A) Vacancies (B) Dislocations (C) Stacking faults (D) Grain boundaries

G-META-12-10

MCQS

A

Material manufacturing

Floatation beneficiation is based on the principle of (A) Mineral surface hydrophobicity (B) Gravity difference (C) Chemical reactivity (D) Particle size difference

G-META-12-11

MCQS

B

Material Applications

Copper can be reduced from acidic copper sulphate solution by (A) Silver (B) Iron (C) Carbon (D) Lead

G-META-12-12

MCQS

C

Material manufacturing

Which one is NOT an agglomeration process? (A) Nodulizing (B) Briquetting (C) Roasting (D) Pelletizing

G-META-12-13

MCQS

D

Material manufacturing

During LD blow in steelmaking the impurity that gets removed first is (A) Carbon (B) Phosphorous (C) Manganese (D) Silicon

G-META-12-14

MCQS

A

Thermodynamics

During the solidification of a pure metal, it was found that dendrites are formed. Assuming that the liquid-solid interface is at the melting temperature, the temperature from the interface into the liquid (A) Decreases (B) Increases (C) Remains constant (D) Increases and then decreases

G-META-12-15

MCQS-NUM

B

Atomic structure

A peak in the X-ray diffraction pattern is observed at 2θ = 78°, corresponding to {311} planes of an fcc metal, when the incident beam has a wavelength of 0.154 nm. The lattice parameter of the metal is approximately (A) 0.6 nm (B) 0.4 nm (C) 0.3 nm (D) 0.2 nm

G-META-12-16

MCQS

B

Atomic structure

If d is the inter-planar spacing of the planes {h k l}, the inter-planar spacing of the planes {nh nk nl}, n being an integer, is (A) d (B) d/n (C) nd (D) d/$n^2$

G-META-12-17

MCQS

C

Electrical

As temperature increases, the electrical resistivities of pure metals ($ρ_m$) and intrinsic semiconductors ($ρ_s$) vary as follows (A) Both $ρ_m$ and $ρ_s$ increase (B) Both $ρ_m$ and $ρ_s$ decrease (C) $ρ_m$ increases and $ρ_s$ decreases (D) $ρ_m$ decreases and $ρ_s$ increases

G-META-12-18

MCQS

B

Thermodynamics

At equilibrium spacing in a crystalline solid, which of the following is true for net inter-atomic force (F) and potential energy (U) (A) F is zero and U is zero (B) F is zero and U is minimum (C) F is minimum and U is zero (D) F is minimum and U is minimum

G-META-12-19

MCQS

D

Thermodynamics

The property of a material that CANNOT be significantly changed by heat treatment is (A) Yield strength (B) Ultimate tensile strength (C) Ductility (D) Elastic modulus

G-META-12-20

MCQS

A

Atomic structure

A unit dislocation splits into two partial dislocations. The correct combination of the Burgers vectors of the partial dislocations for a given unit dislocation having Burgers vector (a/2)[1 -1 0] is (A) (a/6)[2 -1 1] and (a/6)[1 -2 -1] (B) (a/6)[1 -1 2] and (a/6)[-1 -2 1] (C) (a/6)[1 1 -2] and (a/6)[2 -1 -1] (D) (a/6)[2 1 1] and (a/6)[1 2 -1]

G-META-12-21

MCQS

C

Mechanical

A polymer matrix composite is reinforced with long continuous ceramic fibres aligned in one direction. The Young’s moduli of the matrix and fibres are $E_m$ and $E_f$ respectively, and the volume fraction of the fibres is f. Assuming iso-stress condition, Young’s modulus of the composite $E_C$ in a direction perpendicular to the length of fibres, is given by the expression (A) $E_C$ = (1-f)$E_m$ + f$E_f$ (B) $E_C$ = f$E_m$ + (1-f)$E_f$ (C) 1/$E_C$ = [(1-f)/$E_m$] + f/$E_f$ (D) 1/$E_C$ = [f/$E_m$] + (1-f)/$E_f$

G-META-12-24

MCQS

C

Material manufacturing

The riser is designed such that the melt in the riser solidifies (A) Before casting solidifies (B) At the same time as casting solidifies (C) After casting solidifies (D) Irrespective of the solidification of the casting

G-META-12-25

MCQS

D

Atomic structure

Radiography technique of detecting defects is based on the principle of (A) Diffraction (B) Reflection (C) Interference (D) Absorption

G-META-12-31

MATCH

A

Transport phenomena

Match the principles given in Group I with corresponding corrosion terminology in Group II: Group I : [P. Electrode polarization, Q. Passivity, R. Selective leaching, S. Grain boundary precipitation] Group II: [1. Dezincification, 2. Intergranular attack, 3. Over voltage, 4. Surface oxide film] Options: (A) P-3, Q-4, R-1, S-2 (B) P-3, Q-4, R-2, S-1 (C) P-4, Q-2, R-1, S-3 (D) P-2, Q-1, R-4, S-3

G-META-12-32

MCQS

C

Electrical

Identify the correct combination of the following statements: P. Hydrogen electrode is a standard used to measure redox potentials Q. Activation polarization refers to electrochemical processes controlled by reaction sequence at metal-solution interface R. Potential-pH diagrams can be used to predict corrosion rates of metals S. Cathodic protection can use sacrificial anodes such as magnesium (A) P, Q and R (B) Q, R and S (C) P, Q and S (D) P, R and S

G-META-12-33

MCQS-NUM

B

Thermodynamics

Consider a reaction with activation energy of 8.314 kJ/mol that takes place at 300 K. If the reaction rate is to be tripled, the temperature of the reaction should be (A) 174.5 K (B) 447.5 K (C) 600.5 K (D) 847.5 K

G-META-12-34

MATCH

D

Material processing

Match the processes in Group I with the objectives in Group II: Group I : [P. Vacuum Arc Degassing (VAD), Q. LD, R. COREX, S. Blast Furnace] Group II : [1. Primary iron making, 2. Secondary steel making, 3. Direct smelting, 4. Primary steel making] Options: (A) P-3, Q-4, R-2, S-1 (B) P-4, Q-3, R-1, S-2 (C) P-3, Q-2, R-1, S-4 (D) P-2, Q-4, R-3, S-1

G-META-12-35

MCQS-NUM

D

Thermodynamics

The reduction of FeO with CO gas in co-current flow is given by the following equation: FeO + CO = Fe + $CO_2$ ∆G°= 8120 J at 1173K. The ratio of $p_(CO)/p_(CO_2)$ for this reaction at 1173 K is (A) 0.0 (B) 0.25 (C) 0.44 (D) 2.3

G-META-12-36

MCQS-NUM

B

Material manufacturing

The sulphide capacity ($C_S$) of liquid slag of composition 55 wt.% CaO, 20 wt.% SiO2, 15 wt.% Al2O3, and 10 wt.% MgO is given by the following equation: log $C_s$ = 3.44* [$X_(CaO)$ + 0.1*$X_(MgO)$ -0.8*$X_(Al_(2)O_(3)) - $X_(SiO_2)$] - (9894/T) + 2.05 where, X is mole fraction of the respective components. Atomic weights of Ca, Mg, Si, Al and O are 40, 24, 28, 27 and 16 respectively. The value of $C_S$ at 1900 K is (A) 0.0009 (B) 0.009 (C) 0.09 (D) 0.9

G-META-12-39

MATCH

C

Phase transition

Match the phases of steel in Group I with the crystal structures in Group II: Group I: [P. Martensite, Q. Cementite, R. Austenite, S. Ferrite] Group II: [1. bcc, 2. fcc, 3. bct, 4. Orthorhombic] Options: (A) P-3, Q-4, R-1, S-2 (B) P-2, Q-3, R-1, S-4 (C) P-3, Q-4, R-2, S-1 (D) P-4, Q-3, R-2, S-1

G-META-12-40

MCQS

A

Material manufacturing

Arrange the following in terms of increasing severity of quench: P. Oil quenching, Q. Water quenching, R. Water quenching with agitation, S. Brine quenching (A) P<Q<R<S (B) Q<R<P<S (C) P<Q<S<R (D) Q<P<R<S

G-META-12-41

MCQS

D

Material processing

Regarding recrystallization, which one of the following statements is NOT correct? (A) Higher the amount of cold work, lower is the recrystallization temperature (B) Higher the recovery, higher is the recrystallization temperature (C) Higher the temperature of cold work, higher is the recrystallization temperature (D) Finer the initial grain size, higher is the recrystallization temperature

G-META-12-43

MATCH

C

Mechanical

Match the phenomena listed in Group I with the possible mechanisms in Group II: Group I: [P. Fatigue, Q. Creep, R. Strain hardening, S. Yield point phenomenon] Group II: [1. Grain boundary sliding, 2. Slip band extrusion and intrusion, 3. Cottrell atmosphere, 4. Dislocation interaction] Options: (A) P-2, Q-3, R-4, S-1 (B) P-2, Q-4, R-3, S-1 (C) P-2, Q-1, R-4, S-3 (D) P-1, Q-2, R-4, S-3

G-META-12-44

MCQS-NUM

C

Mechanical

Fracture stress for a brittle material having a crack length of 1 µm is 200 MPa. Fracture stress for the same material having a crack length of 4 µm is (A) 200 MPa (B) 150 MPa (C) 100 MPa (D) 50 MPa

G-META-12-45

MCQS-NUM

B

Mechanical

The flow stress (σ) of an alloy varies with strain rate (ε) as σ = 100* $(ε)^(0.1)$ MPa. When the alloy is hot extruded from 10 cm diameter to 5 cm diameter at a speed of 2 cm/s, the flow stress is (A) 1000 MPa (B) 105 MPa (C) 150 MPa (D) 1050 MPa

G-META-12-46

MCQS

C

Material processing

Determine the correctness or otherwise of the following Assertion (a) and Reason (r). Assertion : During rolling, front tension and (or) back tension are (is) employed to decrease rolling load. Reason : Roll pressure decreases due to lowering of flow stress as a result of front tension/back tension. (A) a is false but r is true (B) a is true and r is also true, but r is not the reason for a (C) a is true and r is also true, and r is the reason for a (D) a is true but r is false

G-META-12-47

MATCH

C

Material processing

Match the defects listed in Group I with the processes listed in Group II: Group I : [P. Cold shut, Q. Earing, R. Alligatoring, S. Shrinkage porosity] Group II : [1. Rolling, 2. Forging, 3. Deep drawing, 4. Fusion welding] Options: (A) P-2, Q-4, R-1, S-4 (B) P-2, Q-4, R-3, S-1 (C) P-2, Q-3, R-1, S-4 (D) P-4, Q-1, R-2, S-3

G-META-12-49

MCQS-NUM

B

Fluid

A steel ball (density $ρ_(steel)$ = 7200 kg/$m^(3)$) is placed in an upward moving liquid Al (density $ρ_(Al)$ = 2360 kg/$m^(3)$, viscosity $μ_(Al)$ = 1*$10^(–3)$ Pa.s and Reynolds number = 5*$10^(5)$). The force (F) exerted on the steel ball is expressed as: F = f π $R^(2)$ ($ρ_(Al)$ $v^2$ /2) where, f is friction factor (=0.2), v is the velocity of liquid Al and R is the radius of steel ball. The terminal velocity of a fine spherical steel particle having diameter $d_p$, in µm range, if allowed to fall in a quiescent liquid Al bath, is (A) 5.2*$10^6$ $d_(p)^2$ m/s (B) 2.6* $10^6$ $d_(p)^2$ m/s (C) 1.3*$10^6$ $d_(p)^2$ m/s (D) 6.6* $10^5$ $d_(p)^2$ m/s

G-META-12-52

MCQS-NUM

A

Atomic structure

A material with grain size of ASTM No. 6 has a lattice frictional stress 100 MN/$m^2$ and locking parameter (Hall-Petch constant) 0.10 MN/$m^(1.5)$. Grain size of the material is approximately (A) 45 µm (B) 35 µm (C) 4.5 µm (D) 3.5 µm

G-META-12-53

MCQS-NUM

B

Mechanical

A material with grain size of ASTM No. 6 has a lattice frictional stress 100 MN/$m^2$ and locking parameter (Hall-Petch constant) 0.10 MN/$m^(1.5)$. Yield strength of the material is approximately (A) 100 MPa (B) 115 MPa (C) 165 MPa (D) 215 MPa

G-META-13-3

MCQS

A

Thermodynamics

In a binary system A-B, $ε_(AA)$, $ε_(BB)$ and $ε_(AB)$ correspond to A-A, B-B and A-B bond energies respectively. The miscibility gap will occur if (A) $ε_(AB)$ > ½ ($ε_(AA)$ + $ε_(BB)$) (B) $ε_(AB)$ < ½ ($ε_(AA)$ + $ε_(BB)$) (C) $ε_(AB)$ = ½ ($ε_(AA)$ + $ε_(BB)$) (D) $ε_(AB)$ < ¼ ($ε_(AA)$ + $ε_(BB)$)

G-META-13-5

MCQS

A

Atomic structure

With respect to the matrix of Al-Cu alloys, G-P zones are (A) coherent (B) incoherent (C) semi-coherent (D) chemically indistinguishable