357. Air-petrol ratio for maximum power generation in spark ignition engine is about
A. 6:1
B. 12 : 1
C. 18 : 1
D. 24 : 1
✅ The correct answer is option B.
360. High endurance limit of carburised machine parts is because of the fact that carburisation
A. Suppresses any stress concentration produced in the parts
B. Enhances the yield point of the material
C. Introduces a compressive layer on the surface
D. Produces a better surface finish
✅ The correct answer is option C.
363. Heating of ferromagnetic materials to a temperature above Curie temperature makes it
A. Insulator for heat & electricity transmission
B. Ferritic
C. Behave like paramagnetic materials
D. Superconductor
✅ The correct answer is option C.
366. Sudden immersion/dipping of red hot steel bar in water makes it
A. Malleable & tough
B. Ductile & soft
C. Brittle & hard
D. None of these
✅ The correct answer is option C.
369. Pressure gauges are never connected directly to the live steam line; rather a loop or syphon is interposed as close as possible to the pressure gauge. This is done to
A. Avoid the overheating of the tubes & bellows which operate them to minimise error and damage
B. Form a seal of water by steam condensate to fill the tube or bellows at the pressure being measured
C. Both ‘a’ & ‘b’
D. Avoid the static head error introduced by steam entry
✅ The correct answer is option C.
372. All radiations falling on a black body are
A. Refracted
B. Reflected
C. Transmitted
D. Absorbed
✅ The correct answer is option D.
375. The magnitude of water hammer caused in pipe flow is independent of the
A. Pipe length
B. Fluid flow stoppage rate
C. Fluid temperature
D. Time of valve closure
✅ The correct answer is option C.
377. Maximum permissible sulphur content in steel is __________ percent.
A. 0.015
B. 0.055
C. 0.505
D. 0.805
✅ The correct answer is option A.
379. Propulsion of rocket follows from the
A. Newton’s second law of motion
B. Newton’s third law of motion
C. Law of projectiles
D. Archimedes principle
✅ The correct answer is option B.
343. Minimum safe distance between two liquid fuel storage tanks is equal to (where, H = height of the tank)
A. H
B. H/2
C. H/4
D. H/6
✅ The correct answer is option D.