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21.

Consumable patterns are made of

A.	polystyrene	B.	wax
C.	plaster of paris	D.	any of the above

22.

There is no need for the withdrawal of pattern from the mould in case of

A.	wax patterns	B.	hollow patterns
C.	patterus with core	D.	consumable patterns

23.

In case of consumable patterns

A.	labour charges are reduced	B.	core is not required
C.	moulds are unsplit	D.	all of the above

24.

Polystyrene often used as a consumable pattern material has a relative density of

A.	20 to 25 kg/m3	B.	120 to 125 kg/m3
C.	1120 to 1125 kg/m3	D.	2240 to 2500 kg/m3

25.

Polystyrene is generally available in the form of

A.	plates	B.	cylindrical bars
C.	square sections	D.	trapezoidal moulds

26.

Wood used for pattern making has knots. This is likely to affect

A.	warping of the piece	B.	machinability of pattern
C.	moisture content of wood	D.	all of the above

27.

While selecting wood for patterns, one should

A.	discard the rot	B.	select the cross-grained woods
C.	select the fresthy filled wood	D.	discard the seasoned wood

28.

Which wood is difficult to machine?

A.	Freshly failed wood	B.	Old and used wood
C.	Kiln dried wood	D.	Seasoned wood

29.

On drying, wood

A.	expands	B.	shrinks
C.	changes colour

30.

On drying the shrinkage of wood is least

A.	along the grains	B.	across the grains
C.	along the direction of tangent to the annular rings