261. Presence of high amount of silicon in cast iron
Suppresses the decomposition of Fe₃ C
Increases the formation of graphite
Increases the contraction of the metal
Reduces its fluidity
✅ The correct answer is option B.
Materials and Construction MCQs
262. Which one occupies the lowermost position in the electromotive series of metals?
Aluminium
Noble metals (Ag, Pt, Au)
Zinc
Alkali metals (K, Na, Li)
✅ The correct answer is option B.
263. The carbonating tower used in Solvay process of soda ash manufacture is made of
Cast iron
Stainless steel
Karbate
Lead lined steel
✅ The correct answer is option A.
264. Sulphuric acid is mixed with ground phosphate rock (to produce phosphoric acid) in a steel digestor lined with
Acidic refractory
Rubber
Karbate
Lead or acid-proof bricks
✅ The correct answer is option D.
265. Vycor, a widely used material for making ‘thermal wells’ in temperature measurement, is a
Cermet
Glass
Thermosetting plastic
Metallic alloy
✅ The correct answer is option B.
266. Sheardising process is used for
Surface coating
Heat treatment of high speed steel
Cold working on metals
None of these
✅ The correct answer is option A.
267. The temperature at which new grains are formed in the metal is called the __________ temperature.
Eutectic
Recrystallisation
Upper critical
Lower critical
✅ The correct answer is option B.
268. __________ is used for examining the macro-structure of a material.
Metallurgical microscope
Optical microscope
X-rays
Visual inspection by naked eye
✅ The correct answer is option D.
269. Zinc is not used
For producing zinc base die casting alloys
In its oxide form as pigments
As anode for corrosion prevention in boiler
As an alloying element in various bronzes
✅ The correct answer is option D.
270. Thermal shield used in high powered nuclear reactor to protect the walls of the reactor from radiation damage is made of
Concrete
Steel
Zircalloy
Graphite
✅ The correct answer is option B.