Every object moves with a constant speed. This is not correct because some objects can move with a changing speed. This type of motion is known as non-uniform motion.

The time period of a given pendulum is not constant. This statement is not correct because moves in a to-and fro motion and completes an oscillation when the bob moves from one extreme end to another extreme end and returns back to initial position. This type of motion is known as oscillatory motion. The time taken by the pendulum to complete one oscillation is known as time period of a given pendulum. The time period doesn’t vary with a slight change in its initial displacement and hence the time period remains constant.

The speed of train is expressed in m/h. This statement is not correct. The speed of a train is expressed in km/h.