$A$ ball is dropped and its displacement versus time graph is as shown (Displacement $x$ from ground and all quantities are positive upwards).
$(a)$ Plot qualitatively velocity versus time graph.
$(b)$ Plot qualitatively acceleration versus time graph.

(N/A) It is clear from the graph that displacement $x$ is positive during motion. The ball is dropped from a height and its velocity increases in the downward direction due to the gravitational field. In this condition,$v$ is negative,but the acceleration of the ball is equal to the acceleration due to gravity,i.e.,$a = -g$.
When the ball rebounds in the upward direction,its velocity is positive,but the acceleration remains $a = -g$.
$(a)$ The velocity-time graph of the ball is shown in fig. $(i)$.
$(b)$ The acceleration-time graph of the ball is shown in fig. $(ii)$.