050/23

. Which of the following statements is true with regard to Atomic Packing Factor (APF) ?
A) APF of FCC is equal to APF of HCP
B) APF of SC is greater than APF of BCC
C) APF of BCC is greater than APF of HCP
D) APF of BCC is equal to APF of FCC

. Which of the following pairs is matched correctly ?
A) Surface defect — Presence of extra partial planes
B) Point defect — Precipitates

C) Line defect - Grain boundary

D) Volume defect — Slag and porosity

. Which of the following is true for Burger’s vector in edge dislocation ?
A) Perpendicular to the dislocation line B) Parallel to the dislocation line
C) Inclined to the dislocation line D) None of these

. A typical metallic sheet of 10 mm thickness and cross-sectional area of 0.25 m2? is
used as a steady state diffusion membrane in a hydrogen purifier. Find the mass
of hydrogen purified in kg per second, if the difference in hydrogen concentration
across the sheet is 1 kg/m® and the diffusion coefficient is 1 x 10-8 m/s.

A) 4x 10-6 8) 2.5x 10-7 C) 5x 10-7 D) 3x 10-6

. Which of the following are true for austenite ?
i. It is a solid solution of iron, carbon and chromium
ii. It has FCC crystal structure
iii. It is stable at room temperature
iv. Pure austenite is stable in the temperature range of 912 — 1394°C
A) iandii B) ii and iii C) iandiv D) ii and iv
. Which of the following statements agree with the Hume-Rothery Rules for solid
solubility ?
A) The size difference between solvent and solute atoms must be less than 15%
B) Crystal structure of both the materials must be different
C) There should be large difference in electronegativity of the materials
D) The valency of the atoms of the materials must be different

. In eutectic reaction, which of the following is true ?
A) Liquid + 5-ferrite < Austenite 8) Austenite © o-Ferrite + Cementite
C) Liquid <> Austenite + Cementite D) Ferrite < Austenite + Cementite