$(i)$ If one states that' the car has travelled $100 m ^{\prime}$, it means that it is the distance travelled by the car. But if one states that 'car has travelled $100\, m$ due north' it means that the displacement of the car is $100\, m$ towards north.

$(ii)$ If a body starts its motion from a point and comes back to its initial position after a a al positon a a certain time, the displacement is zero, the average velocity is also zero. but the total distance travelled is not zero and, therefore the average speed is not zero.

$(iii)$ The motion of a car in a busy market is with variable velocity. In such a case, if the velocity of the body increases with time, the motion is said to be accelerated while if the velocity of the body decreases with time, the motion is said to be retarded