In a synchronous motor, If the load angle exceeds 90°, then the motor will: 

Concept:

In a synchronous motor, the load angle (also called torque angle) is the angle between the rotor magnetic field and the stator magnetic field. As the load increases, this angle increases. However, the motor can only maintain synchronism up to a certain maximum angle, typically close to 90°.

Given

Machine: Synchronous motor

Condition: Load angle exceeds 90°

Calculation

When the load angle increases beyond 90°, the torque developed by the synchronous motor starts to decrease. At this point, the motor can no longer produce sufficient torque to drive the load and loses synchronism. Since synchronous motors do not have self-starting torque, once synchronism is lost, the motor stalls.

Other options like reduced copper losses, increased efficiency, or leading power factor operation are unrelated to the loss of synchronism due to load angle exceeding 90°.

Final Answer:  Lose synchronism and stall.