408. Fire refining process is employed in case of
A. Tin
B. Copper
C. Zinc
D. Aluminium
✅ The correct answer is option B.
411. Multistage compression is necessary for high efficiency,
A. If the ratio of the delivery pressure to the intake pressure exceeds 5:1
B. When large amount of gas is to be compressed
C. When the delivered gas is desired at very high velocity
D. None of these
✅ The correct answer is option A.
414. Which of the following pair is correctly matched?
A. Heat transfer: Thermal diffusivity
B. Mass transfer: Diffusion co-efficient
C. Momentum transfer: Kinematic viscosity
D. All of the above
✅ The correct answer is option D.
417. The laminar boundary layer thickness in zero pressure gradient flow over a flat plate along the x-direction varies as x0.5 while the thickness of turbulent boundary layer varies as (where, x = distance from the leading edge)
A. X1.5
B. X0.8
C. X-1.5
D. X-0.8
✅ The correct answer is option B.
381. Which of the following materials has the poorest electrical conductivity?
A. Carbon
B. Aluminium
C. Silver
D. Stainless steel
✅ The correct answer is option A.
384. Normalising of an object does not
A. Refine coarse grain structure obtained during hot working
B. Improve ductility
C. Improve yield strength
D. Improve machanical properties
✅ The correct answer is option B.
387. The following type of bonding is strongly directional in solids.
A. Vander Waal’s
B. Ionic
C. Metallic
D. Covalant
✅ The correct answer is option D.
390. Magnesium is present in
A. Haemoglobin
B. Chlorophyll
C. Hypo solution
D. None of these
✅ The correct answer is option B.
393. Magnesium addition to cast iron increases its
A. Corrosion resistance
B. Creep strength
C. Ductility and strength in tension
D. Hardness
✅ The correct answer is option C.
395. A material having good damping property is likely to have
A. Greater defect density
B. Fine grained structure
C. Lesser defect density
D. High tensile strength
✅ The correct answer is option A.