541. Preheating prior to welding is done for the purpose of
A. Decreasing cooling rate
B. Facilitating fusion of high melting metals
C. Preventing hot cracking
D. Ensuring full penetration
✅ The correct answer is option A.
543. In a neutral solution
A. H⁺ ions are absent
B. OH⁻ ions are absent
C. Both H⁺ and OH⁻ ions are present in very small but equal concentration
D. None of these
✅ The correct answer is option C.
545. A pipeline buried in soil is commonly protected from corrosion by
A. Anodic protection
B. Cathodic protection
C. Using inhibitors
D. Using a special alloy resistant to corrosion
✅ The correct answer is option B.
547. Diffusion co-efficient of a metal in a solid solution depends upon its
A. Composition
B. Temperature
C. Both A & B
D. Neither A nor B
✅ The correct answer is option C.
549. A balanced draught boiler furnace employs __________ draught fan.
A. Induced
B. Forced
C. Both A & B
D. Neither A nor B
✅ The correct answer is option C.
552. Which of the following is not used as a bearing material?
A. Copper-lead alloys
B. Babbits
C. Bronzes
D. Cermets
✅ The correct answer is option D.
555. The gases used in the treatment of asthma is a mixture of __________ and oxygen.
A. Helium
B. Argon
C. Neon
D. None of these
✅ The correct answer is option A.
558. Annealing of a material does not
A. Permit its further cold working
B. Soften it
C. Case harden it
D. None of these
✅ The correct answer is option C.
561. Shampoos are commercially not available in the form of
A. Powder
B. Gaseous mixture
C. Solution
D. Emulsion
✅ The correct answer is option B.
564. Stoneware pipes used for sewers for carrying sewage normally is joined by __________ joint.
A. Spigot and socket
B. Flanged iron
C. Collar
D. Expansion
✅ The correct answer is option A.