Theory of Machine
A combination of kinematic pairs, joined in such a way that the relative motion between the links is completely constrained, is called a

Mechanism
Structure
Kinematic chain
Inversion

ANSWER DOWNLOAD EXAMIANS APP

Theory of Machine
Open pairs are those which have

Elements of pairs not held together mechanically
Two elements that permit relative motion
Surface contact between the two elements when in motion
Point or line contact between the two elements when in motion

ANSWER DOWNLOAD EXAMIANS APP