11. In coding of electrodes, radiographic quality electrodes is indicated by the letter ……….
(a) A
(b) X
(c) Y
(d) Z
12. Why is oxidising flame considered suitable for welding of brass and bronze?
(a) Melting point of brass and bronze is high
(b) This type of flame helps retain colour of brass and bronze
(c) This type of flame avoids vaporisation of zinc
(d) This type of flame helps in increasing speed of welding
13. Welding nearer to the neutral axis of a T-fillet joint helps to reduce the effect of ………
(a) Arcblow
(b) Longitudinal contraction
(c) Shrinkage forces in the joint
(d) High thermal expansion of base metal
14. Heat is measured in ……
(a) Joules
(b) Kilogram
(c) Calories
(d) Both (a) and (c)
16. An electrical circuit is a path taken by flow of current. A path with no breaks is called ……
(a) Closed circuit
(b) Open circuit
(c) Continuous circuit
(d) Limited circuit
17. What is the most common (maximum percentage) gas in the atmosphere?
(a) Oxygen
(b) Carbon dioxide
(c) Nitrogen
(d) Methane
18. Welding is not done directly from the supply mains because ……..
(a) Its voltage keeps fluctuatin
(b) 1t is impractical to draw heavy current
(c) It is customary to use welding machines
(d) None of the above
19. In arc welding, arc blow can be avoided by ..
(a) Using AC welding machine
(b) Increasing arc length
(c) Using bare electrodes
(d) Welding away from earth ground connection
20. In electrode — positive welding, …… of the total heat is produced at the electrode.
(a) Two — third
(b) One — fourth
(c) One — third
(d) One — half