2.5
2.8
3
3.5
one-half
two-third
three-fourth
double
14.5 Degree composite and full depth involute system
20 Degree full depth involute system
20 Degree stub system
none of the above
friction angle is less than helix angle
friction angle is more than helix angle
friction angle is equal to helix angle
efficiency of screw is 100%
brittle materials
ductile materials
plastic materials
non-ferrous materials