a. I have learnt -Torsional rigidity, Breaking twist, Shear modulus.

b. The twist for breaking of a yarn is called breaking twist. It also can be defined as the number of twists required to break a yarn. Breaking twist depends on the diameter of fiber and it is inversely proportional to its diameter.

That is,

 Tb ∞ 1/d

Where, 

Tb = Breaking twist,

d = diameter of fiber.