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০০। 'Age hardening' of duralumin is due to
- ক) copper
- খ) magnesium
- গ) both (a) & (b)
- ঘ) neither (a) nor (b)
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০১। 'Hypersil' is a __________ steel.
- ক) high speed
- খ) silicon
- গ) molybdenum
- ঘ) tungsten
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০২। 'Semi steel' is
- ক) produced by adding 10-20% steel to the cupola charge.
- খ) stronger than cast iron.
- গ) both (a) and (b).
- ঘ) neither (a) nor (b).
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০৩। 100% H2SO4 at 30°C can't be stored in a vessel made/lined with
- ক) cast iron and high silicon iron.
- খ) mild steel and stainless steel.
- গ) aluminium, tin and rubber.
- ঘ) teflon, glass and porcelain.
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০৪। 18-4-1 high speed steel contains 18%, 4% and 1% respectively of
- ক) tungsten, vanadium and chromium
- খ) tungsten, chromium and vanadium
- গ) vanadium, chromium and tungsten
- ঘ) chromium, tungsten and vanadium
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০৫। 18/8 stainless steel means, that it contains
- ক) 18% chromium and 8% nickel.
- খ) 18% chromium and 8% molybdenum.
- গ) 18% nickel and 8% chromium.
- ঘ) 18% molybdenum and 8% chromium.
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০৬। 18/8 steel is a/an __________ stainless steel.
- ক) austenitic
- খ) ferritic
- গ) martensitic
- ঘ) none of these
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০৭। A bearing metal should not have
- ক) enough plasticity.
- খ) low thermal conductivity.
- গ) low co-efficient of friction.
- ঘ) high toughness.
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০৮। A chemical change takes place when iron
- ক) rusts
- খ) melts
- গ) is heated
- ঘ) none of these
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০৯। A hardened steel essentially contains
- ক) sorbite
- খ) troostite
- গ) martensite
- ঘ) none of these
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১০। A hardness depth of about 3 mm can be achieved by induction hardness in __________ seconds.
- ক) 5
- খ) 100
- গ) 250
- ঘ) 500
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১১। A magnetic material becomes __________ above the Curie temperature.
- ক) ferromagnetic
- খ) diamagnetic
- গ) paramagnetic
- ঘ) none of these
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১২। A material capable of undergoing large permanent deformation, when subjected to compression is termed as
- ক) malleable
- খ) ductile
- গ) brittle
- ঘ) none of these
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১৩। A material capable of undergoing large permanent deformation, when subjected to tension is termed as
- ক) friable
- খ) ductile
- গ) brittle
- ঘ) none of these
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১৪। A material is able to retain the deformation permanently by virtue of its
- ক) elasticity
- খ) plasticity
- গ) ductility
- ঘ) malleability
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১৫। A material is called 'ductile', if it can be
- ক) drawn into wires.
- খ) hammered to a thin sheet.
- গ) fractured without deformation.
- ঘ) made lustrous by heating it.
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১৬। A material no longer behaves elastically beyond
- ক) plastic limit
- খ) limiting load
- গ) elastic limit
- ঘ) breaking load
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১৭। A measure of toughness of a material is its
- ক) percentage elongation
- খ) yield strength
- গ) ultimate strength
- ঘ) area under stress-strain diagram
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১৮। A metallic alloy in general as compared to their pure metal components is
- ক) more corrosion resistant.
- খ) having higher melting point.
- গ) having lower hardness, reactivity and fusibility.
- ঘ) having lower electrical conductivity.
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১৯। A metallic alloy in which one of the constituent metal is __________ , is called an amalgam.
- ক) zinc
- খ) mercury
- গ) lead
- ঘ) tin