Is there an unofficial rule for PPC questions that if a firm is operating at a point under PPC then the Point will move and the PPC will remain constant????
If so, what is the logic behind this rule????
I have never come across a question where a firm is operating at a point under PPC and the PPC shifts.
Is there any example of this case???
PPC shows the maximum producing capacity of an economy (or a firm in your case) with the given resources. If the firm is operating at a point under PPC that means its not fully and efficiently using its resources so it will strive to move towards PPC. The PPC remains the same.