281. Hot tears are casting defects
A.Which occur due to some sand shearing from the cope surface
B.Which take the from of internal voids or surface depression due to excessive gaseous material not able to escape
C.Which occur due to discontinuity in metal casting resulting from hindered contraction
D.Caused by two streams of metals that are too cold to fuse properly

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282. Fetling is an operation performed
A.Before casting
B.During casting
C.After casting
D.After heat treatment

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283. Vertical centrifugal castings as compared to horizontal centrifugal castings are spun at
A.Higher speed
B.Slower speed
C.Same speed
D.Unpredictable

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284. Shell moulding process requires
A.Wooden patterns
B.Sand patterns
C.Plastic patterns
D.Metal patterns

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285. Cold shots are casing defects
A.Which occur due to some sand shearing from the cope surface
B.Which take the form of internal voids or surface depression due to excessive gaseous material not able to escape
C.Which occur due to discontinuity in metal casting resulting from hindered contraction
D.Caused by two streams of metals that are too cold to fuse properly

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286. Slag inclusion in casting is a
A.Surface defect
B.Internal defect
C.Crack
D.Notch

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287. A sprue hole is
A.A casting defect
B.An opening in mould for pouring molten metal
C.A blind hole in jigs
D.An eccentric hole in dies for clamping

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