Answer:
The velocity is zero at one instant, and the acceleration is not zero at that instant.
Step-by-step explanation:
We know that

Where
a is the acceleration of moving object
V is the velocity.
When velocity of object is increasing with time then it means that object is accelerated.
When velocity of object is decreasing with time then it means that object is de-accelerated.
When velocity is constant it means that acceleration of object is zero.
So at particular position the instant velocity of block is zero but acceleration is not zero at that instant.