23.
The riser is designed such that the melt in the riser solidifies

25.
Match the defect with appropriate cause.
List-I List-II
P. Hot tear 1. Inadequate riser
Q. Porosity 2. Loosely rammed sand mould
R. Sand inclusions 3. Mould restraint
S. Shrinkage cavity 4. Gas entrapment

27.
Match the features observed in castings listed in Group I with the most appropriate reasons listed in Group II.
Group I Group II
P. Macrosegregation 1. Inoculation
Q. Fine grained structure 2. Gas evolution and shrinkage
R. Porosity 3. Temperature gradients and supercooling
S. dendrites 4. Density difference and convection currents

28.
Casting alloys with a large freezing range tend to result in
P. shrinkage cavity
Q. distributed shrinkage porosity
R. liquid metal with poorer fluidity
S. liquid metal with superior fluidity

30.
Mould oscillation is used in continuous casting of steels to