With reference to electric arc welding:

(a) Draw a labeled sectional sketch of a satisfactory butt weld. (6)

(b) Briefly define the following defects that may occur and how they may have been caused:

(i) Under cut (2)

(ii) Splatter (2)

(iii) Inclusion (2)

(iv) Blow hole (2)

(v) Incomplete root penetration (2)