The acceleration of the leaf as it falls is zero.
Step-by-step explanation:
There are to forces acting on the leaf;
(a) force of gravity acting downwards
(b)Air resistance acting upwards
At some point force of gravity acting downwards balances the force of air resistance acting upwards and thus the net force on the leaf is zero.As the net force on the leaf is zero, the acceleration of the leaf =0.
Because of this zero net force, the leaf will acquire a constant velocity after some time called as terminal velocity and will continue to move with this constant velocity.