Which of the following statements is correct?i. Density is a scalar quantity.ii. Momentum is a vector quantity.iii. An object can never have zero displacement if it has moved through a distance.iv. If an athletes completes one round of a circular track of diameter 200 m in 40 seconds, the distance covered by him at the end of 2 min 20 will be 2200 m.

The correct statements are:

i. Density is a scalar quantity. This is correct because density only has magnitude and no direction. It is defined as mass per unit volume.

ii. Momentum is a vector quantity. This is also correct. Momentum is the product of mass and velocity, and since velocity is a vector quantity, momentum is also a vector quantity.

iii. An object can never have zero displacement if it has moved through a distance. This statement is incorrect. Displacement is the shortest distance from the initial to the final position of an object. It is possible for an object to move through a distance and still have zero displacement. For example, if an object moves in a circle and returns to its starting point, its displacement is zero.

iv. If an athlete completes one round of a circular track of diameter 200 m in 40 seconds, the distance covered by him at the end of 2 min 20 will be 2200 m. This statement is incorrect. The distance covered by the athlete in one round is the circumference of the circle, which is πd = 3.14 * 200 = 628.32 m. In 2 min 20 sec (or 140 sec), the athlete would complete 140/40 = 3.5 rounds. So, the total distance covered would be 3.5 * 628.32 = 2199.12 m, which is approximately 2200 m. However, this is an approximation and not exactly 2200 m.