Question

Though action and reaction forces are equal in magnitude, yet they may not produce accelerations of equal magnitude.Why?

Answer 1

Action and reaction forces are equal in magnitude, these forces may not produce acceleration of equal magnitudes. This is because each force act on a different object that may have a different mass.
This is so because acceleration is also dependent on the mass of the respective bodies. Acceleration is inversely proportional to mass. This means that even if the forces are equal and opposite in magnitude, yet the objects may have different accelerations due to difference in masses.

or
For a given force, the larger the mass, the lower the acceleration. If you push on an object and it doesn't move, that means the net force must = 0. That means the opposing force is exactly equal to the applied force, they cancel. If the object does move the net force = m*a
That means the applied force = the opposing force + ma OR
applied force - opposing force = ma
Thus for a given applied force the acceleration depends upon the opposing force AND the mass being accelerated.​​​​​​​