Theory of Machine
The two elements of a pair are said to form a higher pair, when they

Have a line or point contact when in motion
Permit relative motion
Are kept in contact by the action of external forces, when in motion
Have a surface contact when in motion

ANSWER DOWNLOAD EXAMIANS APP

Theory of Machine
In a mechanism, the fixed instantaneous centers are those centers which

Moves as the mechanism moves, but joints are of permanent nature
Vary with the configuration of the mechanism
Remain in the same place for all configurations of the mechanism
None of the listed here

ANSWER DOWNLOAD EXAMIANS APP