251. A material is said to be allotropic, if it has
fixed structure at all temperatures
atoms distributed in random pattern
different crystal structures at different temperatures
any one of the above
✅ The correct answer is option C.
Engineering Materials MCQs
252. The steel produced by bessemer or open hearth process is __________ to that produced by L-D process.
superior
inferior
✅ The correct answer is option B.
253. A small percentage of boron is added to steel in order to
increase hardenability
reduce machinability
increase wear resistance
increase endurance strength
✅ The correct answer is option A.
254. The hardness of steel increases if it contains
pearlite
ferrite
cementite
martensite
✅ The correct answer is option C.
255. The electric process of steel making is especially adopted to
alloy and carbon tool steel
magnet steel
high speed tool steel
all of these
✅ The correct answer is option D.
256. Cast iron is a
ductile material
malleable material
brittle material
tough material
✅ The correct answer is option C.
257. Closed packed hexagonal space lattice is found in
zinc, magnesium, cobalt, cadmium, antimony and bismuth
gamma-iron, aluminium, copper, lead, silver and nickel
alpha-iron, tungsten, chromium and molybdenum
none of the above
✅ The correct answer is option A.
258. The heat treatment process used for softening hardened steel is
carburising
normalising
annealing
tempering
✅ The correct answer is option D.
259. The cupola is used to manufacture
pig iron
cast iron
wrought iron
steel
✅ The correct answer is option B.
260. Which of the following has a fine gold colour and is used for imitation jewellery?
Silicon bronze
Aluminium bronze
Gun metal
Babbit metal
✅ The correct answer is option B.