288. The dominant property of cellulosics, a form of thermoplastic plastics is
A.Ease of working and toughness
B.Corrosion resistance and mechanical strength
C.High heat and wear resistance and fine grain structure
D.Good colour, finish, texture and light transmissibility
289. Crystal structure of metals is studied by
A.Metallograph techniques
B.X-ray techniques
C.Ultrasonic method
D.Electron microscopy
290. The grain growth in austenite duringheat treatment of steel can be inhibited by adding
A.Copper
B.Aluminium
C.Nickel
D.Manganese
291. Heat treatment operation involving heating of steel above upper critical temperature and then cooling it in the furnace is known as
A.Annealing
B.Tempering
C.Austempering
D.Normalising
292. Heat treatment operation involving heating of steel above upper critical temperature and then cooling it in air is known as
A.Annealing
B.Tempering
C.Austempering
D.Normalising
293. Tempering temperature of most of the materials is of the order of
A.100-150°C
B.200-300°C
C.350-400°C
D.400-500°C
294. Normalising operation is carried out in
A.Furnace
B.Air
C.Water
D.Oil
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