Which of the following is not true in case of an ideal gas?

As we know from the kinetic theory of gases that in gaseous state, molecules are weekly bound to one another. They are far apart from each other. 

Each molecule in the system will move with its own speed. For example, molecule A move with x speed and molecule B will with speed b. 

While moving, the speed of each remains constant. In other words, they will continue to move with the speed at which they were initially moving.

All molecules move with altogether differently, but at a constant speed